Peter
NOTE: Adobe AIR isn't an open source product, but I think it's worthy of covering anyway due to its potential for bringing greater application compatibility to open source platforms.
Building applications that work across multiple platforms is always a challenge, but the web has provided a solution for some of those problems, by inherently being a cross-platform medium.
Sometimes the web isn't powerful enough, however, and there is no replacement for a desktop application.
Adobe's AIR platform is designed to bring the ease of development and cross platform support of the web and combine it with the benefits of desktop applications.
AIR is a framework for Windows, Mac OS X and now Linux that allows you to build lightweight desktop applications. It is worth mentioning that AIR isn't open source, and is obviously designed in part to push Adobe's platforms, such as Flash, which also aren't free and can be troublesome on Linux and Unix systems.
Ignoring that, Adobe AIR for Linux 1.1 Beta was released a few days ago and allows you to run pretty much any AIR application already written on your Linux system.
Unfortunately, the installation is a little cumbersome and could be a stumbling block unless you know how to use the command line.
The installation does work, however, and AIR applications then seem to run pretty well (I tried Twitter client TweetDeck and it appears to work just as it does on Windows and Mac OS X).
In my book, anything that opens up the Linux platform to more application support can only be a good thing, and despite AIR not being free software itself (it is free of charge, but doesn't meet the FSF definition of free software), I think this is a positive step and definitely worth it if you're already a user of AIR apps on other platforms.
You may want to take a look at the release notes and then download the beta.
