MSDN blog:

Look for Visual Studio 2008 Downloads on Top Subscriber Downloads - Coming Soon

Visual Studio 2008 is anticipated out very soon, with availability for Subscribers. Check out the "Top Subscriber Downloads" area on http://msdn2.microsoft.com/subscriptions for VS 2008 downloads.

You will also be able to access these downloads by clicking on the Subscriber Downloads and Product Keys links that take you to all of your downloads.

We are using two different platforms to make these downloads available - to improve discoverability and reliability, and to balance demands on the systems.

Presumably the public release (especially the free Express products) will be available soon as well.