It was originally planned for last friday, but to hold back the pressure for the support team to enjoy Whitsun and Mother's Day, it was rescheduled to today.

The Service Pack 1 beta (remember its still the beta!) for Visual Studio 2008 and .NET FX 3.5 is officially announced at Somasegar's Weblog

You can find the downloads over here:

Microsoft Visual Studio 2008 Service Pack 1 Beta

and

Microsoft .NET Framework 3.5 Service pack 1 Beta

For me the Visual Studio 2008 Service Pack 1 is an important release as just after Visual Studio 2008 going RTM I hit and filed a bug where it appeared that cached data in document customizations corrupted in scenarios working with protected documents. I worked out a script to repro this and the VSTO team worked real hard to get this out of the way. The fix is now available in this release:

328329 The data cache is corrupted when protected word customizations exist.

This is fixed issue number four and the complete list of VSTO related fixes is available in this document:
http://support.microsoft.com/kb/949258/

Besides fixing VS it also requires you to make some code changes to get it all to work. I will get back on that in one of my next blog items. 

The VS2008 SP1 beta release notes and a pointer to the document above are available in this document:
http://support.microsoft.com/kb/945140/

Happy testing!