Microsoft has now released the final bits of Visual Studio 2008 Service Pack 1 and the .NET Framework 3.5 Service Pack 1, download here. A lot of stuff has been improved such as stability and performance, no need for me to repeat all this since you can find it a gazillion of blogs as well as in the Microsoft Knowledge Base.
One improvement I did not read about is that they have fixed/updated the icon of the devenv.exe so you can distinguish VS 2008 and VS 2005 if you are running them simultaneously. The VS 2008 SP1 icon contains a 9 in the lower right corner.
Look at the icons in the images below; from left to right it is Visual Studio 2005, Visual Studio 2008 RTM and Visual Studio 2008 SP1. The 2008 version is a bit more glossy, but the smallest icons look pretty similar (VS 2005 on top).