As I work with a highly customized Visual Studio 2008 environment a bug introduced with SP1 for Visual Studio 2008 was one of the worst in history (for me): VS Dev Environment crash after undocking windows or changing layouts .
In case you are like me and did not have the luck to find this “not really visible fix”(tm) yet just click here and you’ll back to your normal-customized VS interface (yeah, multi-mon makes sense again, even for VS 
)
Best regards,
- t
(*) = one of the worst bugs for me!