I suspect this will be pretty widely advertised fairly quickly, but both Visual Studio 2008 SP1 and .NET 3.5 SP1 are available for download. Personally I’ve had problems signing into the MSDN subscriptions site and going to the downloads page, but the direct links work fine. Both are fairly small files which then download more stuff when you execute them. The .NET 3.5 SP1 download doesn’t require you to have .NET 3.5 installed beforehand.
Update (13th August): Patrick Smacchia has a great post showing the differences (in terms of numbers rather than features) between 3.5 and 3.5SP1.