There is a python script avaliabe that lets you play a startup sound. It wont play a whole playlist (I don't think) but it will let you play a song of your choice, or the default start up sound. I don't think this is really want but it gives you an anwer.

Currently you can't make it play a playlist from startup in XBMC. The other thing you could do is to make the startup screen (instead of progs, vids, music, setup etc) the music folder of your choice - that way you just have to press A to play it. Probably not the answer you wanted but there are some alternatives. There maybe a CVS with the functionality you want. :huh: Perhaps (and there is a good chance I'm wrong!) you could make it stream some music off the internet (shoutcast etc) as the startup song, which would give you variety. Hope that helps.
Maybe I will give it a chance tomorrow..... <