Yay! Soundtrack news!
The quick and dirty upshot:
Caprica's soundtrack will be available from La-La-Land in late May, and in stores in early June.
BSG Season 4 is set for the middle of July. It'll be two discs, with the first CD containing music from "He That Believeth In Me" to "Islanded in a Stream of Stars," and the second CD being pretty much the entire score of "Daybreak."
A soundtrack album for Razor and The Plan will be out sometime after that. That's a bit more vague, because he hasn't even seen The Plan yet, much less finished scoring it. My personal guess would be at the end of the year, since The Plan isn't airing until November, and it doesn't make too much sense to release the soundtrack to it first.
Finally, the multi-CD set of unreleased material from all four seasons is coming at some undetermined point in the future. I very much doubt it'll come out before next year.