Just tried AgileAgenda on Linux (well, Linux inside a VMWare image) with the AIR Linux Alpha and it mostly works.  We'll need to do some tweaking, and it looks like there might be a pretty serious bug with native menus in the AIR Alpha, but it's encouraging.  Still need to do a lot of testing, and probably some more tweaks, but hopefully we can release a Linux version as soon as Adobe releases a decent AIR Beta.