doesn't start apps.
How about checking OS and use Wine to launch apps if needed?
I am now using everything on XP, Vista, and Ubuntu. Plus I have Ubuntu able to run live (and somewhat slower) from my USB drive if I am on a Windows machine. Don't get me wrong, most of my work is still in Windows, but Ubuntu/Wine seems to run everything well, which I manually locate and right click and choose open with Wime. Since these are also open source, free (portable) apps they would seem to be a good match with portableapps.
(Sorry no smart-ass jokes this time.)