MySpace says the following:
You may enter HTML/DHTML or CSS in any text field. Javascript is not allowed. …
It seems like there might be a way to hack it, though. DHTML can be pretty flexible, it seems.
Could Nabble come up with a way to do it through DHTML? It doesn't seem too far of a stretch, but then I haven't used DHTML much.
It sounds like the normal embed tags and iframes should still work, at least.
Maybe it could be done through some embedded Flash, which allows for ActionScript (which is very similar to JavaScript).
Anyway, I hope this helps!