Nah, it definately won't be released before 2008.
Two key factors lead me to that conclusion:
1) It will be released at GenCon Indy (August)
2) it won't be released while there is an Adventure Path running in Dungeon.
#1 should be fairly obvious - that's when all the big releases come out. #2 is a bit less certain, but an Adventure Path in Dungeon provides a lot of groups an incentive to stay with their existing edition until it is completed. By contrast, an Adventure Path that starts just as 4e is released would encourage a lot of groups to switch over. Is the number of groups affected significant? I don't know, but if I were Wizards, I would hold off on approving a new path if I knew 4e was imminent. What's more, I would want to leave a gap between the end of a Path and the big release, because these campaigns take time to play through.
So, since "Savage Tide" starts in September, and therefore finishes in August 2007, that would be a bad time to release 4e. So, I'm betting we'll not be seeing a release until at least 2008.