A Newbie's Guide to Publishing: You Should Self-Publish
For me, the choice to self-publish was never financial motivated; it was about control (primarily of the design of the finished article), but this post from Joe Konrath (a thriller author) goes into great detail on the numbers.
Let's say publishers wise up and begin selling ebooks for $2.99. That would mean authors only get 52 cents from each sale, or 1/4 of what they could make on their own. That's $6k a year in royalties, rather than $24k. If that went on for ten years, an author who signed with a publisher would make $60,000. An author who self-pubbed and sold the same amount of ebooks would make $240,000.
Numbers aside, this pretty much encapsulates a changing industry. An industry that is well and truly on the back foot:
If I look at the poor royalty rates publishers offer, the changing, volatile marketplace, the long time to publication, and then add in the multitude of mistakes publishers continue to make (like high ebook prices), I'd be hard pressed to think of ANY reason to sign a book deal.
So, self publish now. Or approach some publishers who's doing <a href="http://books.alistapart.com%3Ethings%3C/a%3E%20%3Ca%20href="http://www.rosenfeldmedia.com">differently.