just watch for the cs4 announcement. some people are guessing around holiday season 2008 (this year) as a release date. adobe'll usually announce about a month ahead of time.

if you buy the upgrade to photoshop cs3 AFTER the cs4 announcement, but before it ships, you'll be eligible for a free upgrade to cs4 when it is released. at least that's how it's gone in the past.

just this past upgrade cycle i went from illustrator 9 to cs2 after the cs3 announcement and got illy cs3 for free (5 bux shipping) when it shipped.

good luck,
dave