The GNOME release philosophy is to put out releases on a predictable cycle, every six months. A release doesn't need to include major new features or updates, just whatever improvements and features are ready to ship. If a spiffy feature isn't ready by release time, it gets left on the table for the next release or the release after that.
To get into full GNOME 2.18 mode, I installed the Ubuntu Feisty beta, which includes GNOME 2.18, and also test-drove the Foresight Linux release that includes 2.18. I found that the bump from 2.16 to 2.18 is pretty gentle. You're not going to find many differences in this release that really stand out -- it takes some looking.
Seahorse and desktop encryption
The best new feature in 2.18 is Seahorse, an application to manage SSH and Pretty Good Privacy (PGP) keys, as well as support for signing and encrypting and decrypting files from within Nautilus. With Seahorse, GNOME 2.18 has made it almost ridiculously easy to encrypt and decrypt data and sign files. GNOME 2.18 integrates the functions into Nautilus, so all you need to do is right-click on a file to encrypt, decrypt, or sign it. Newbies will be creating keys and encrypting, decrypting, and signing files and email in no time flat.
Seahorse encryption key manager - click to view
Nautilus also now adds a third option for connecting to remote filesystems over SSH. Previously, it would ask whether you wanted to add a password to the keyring permanently, or just for the current session. Now Nautilus also asks if you'd like to forget the password immediately, which is a nice addition for the paranoid among us who don't want to have to sign out of GNOME just to get it to forget a password for a remote server.
GNOME 2.18 also includes a widget-type feature called gDesklets. The idea here is to provide little apps that run on top of the desktop, like weather displays, calendars, RSS aggregators, and GUI applets to display CPU usage. Currently there's a lot of duplication of applets -- you'll find three or four CPU applets, and several disk temperature monitors, for example.
To use them, open the gDesklet Shell and browse the available applets. If you want to run one, just double-click it to make it hover alongside your mouse pointer. You can then drop it onto the desktop itself.
The gDesktlets are a great idea, but they're not yet 100% stable. Under Foresight the gDesklet application wouldn't even launch. Under Feisty, some of the gDesklets behaved fine, but when I tried to launch one of them -- a taskbar replacement -- it wouldn't detach from the mouse to the desktop, and I had to hard-kill the gDesklet daemon and manager to get my pointer back. Most of the applets ran just fine, though.
I'm disappointed that the only help associated with the gDesklets Shell application is the About dialog and tips of the day.
Overall, gDesklets are neat, but I think it will probably be GNOME 2.20 before the software is fully usable.
GNOME Disk Usage Analyzer
GNOME 2.18 brings a few changes to Baobab, otherwise known as the GNOME Disk Usage Analyzer, a utility to display a visual indication of filesystem disk space usage.
With this release, Baobab includes a revved-up display that shows the filesystem in a ring chart layout, as shown here. This is a nifty feature, but it's been present in the similar Filelight utility for some time -- and Filelight gives you the option of drilling down to individual files and even viewing, opening, and deleting them straight from Filelight. In Baobab you can drill down to the directory view, but not to individual files.
Figure 1: GNOME Disk Usage Analyzer - click to view
This release also removes the file search feature from Baobab. I couldn't find anything in the application's changelog or on the Baobab project page to indicate why the functionality was dropped, but I assume it was probably because GNOME already includes a file search feature under the Places menu.
All work and no play, yadda, yadda, yadda
Each release of GNOME comes with a collection of "five-minute games" so users can blow off a little steam. This release adds a Sudoku game to the mix, which might go a bit beyond the five-minute timeframe.
GNOME 2.18 also adds glChess. If OpenGL is available, glChess will display a nice 3-D chess board, or will default to 2-D if it's not. You can play against the computer or against friends over the network.
There's bad news if you're an Ataxx fan, though. It was removed from GNOME after the project conducted a survey to see what games should be included or removed. It's still available from CVS, but no longer distributed as part of "official" GNOME.
In addition to new applications, lots of existing programs received a little new feature love. For example, the Tomboy note-taking application now does bullets; if you enter * or - before a sentence, Tomboy will change it to a bullet and start a bulleted list for you.
Evince now sports browser-like navigation, so you can jump back and forth through a PDF in the same way you'd move through a Web site. You can also open multiple instances of a document using Evince now, which helps if you're reading a contract or another long document that requires you to look at multiple pages at the same time. Unfortunately, the browser-like features don't extend to bookmarks; Evince will open a document at the last page you were viewing, but it doesn't allow you to create bookmarks throughout the document. Evince isn't alone here -- I haven't found a free software PDF viewer that does do bookmarks -- but I don't understand why this obvious feature hasn't been included in any of them.
The overall GNOME desktop
After using the latest version for more than a week, I think GNOME is still a fine desktop, but I'm underwhelmed at the changes between 2.16 and 2.18. It's a solid release, but it doesn't move the ball forward very far in terms of improvements, new applications, or new features.
In fact, it seems that some apps have stagnated a bit. Evolution doesn't offer any significant new features in 2.18, nor does Epiphany nor many of the other "official" GNOME apps.
While working on this review, I noticed several developers on Planet GNOME talking about ideas for the next release, a roadmap process, and the need to start thinking about a GNOME 3.0 or next-gen GNOME, so maybe GNOME will come up with some radical improvements in the nearish future. I suspect that KDE 4.0 will provide a kick in the pants for GNOME folks to think about "catching up" when KDE 4.0 is released.
If you want to try out GNOME 2.18 without the hassle of installing it, and without the wait for your favorite distro to distribute packages, the GNOME team has live CDs and VMware/Qemu/Parallels images of Foresight Linux that you can use to run GNOME 2.18 instead. The Get Footware page on GNOME's site includes a list the GNOME version used by Linux distros and other OSes, so you can check that site to see which distros include GNOME 2.18.