I guess SourceForge hasn't updated its mirrors yet. The files are there on the admin side, but not on the user side. I have no idea how long that will take. It's always been immediate in the past.
Edit: SourceForge is updated now.
BitcoinTalk
Re: Please upgrade to 0.3.8!
From:
satoshi
Subject:
Re: Please upgrade to 0.3.8!
Date: