I found a number of folks using a MacBook Pro for .NET Development:

Visual Studio.NET development on OS X w/ Parallels

Anyone using Visual Studio in Parallels on a MacBook Pro? (lots of good comments here)

A few weeks with a MacBook Pro, Parallels, and MSDN Universal

But in the end I decided I wasn’t ready to make “the switch” just yet for a number of different reasons:

• I do almost 100% .NET development
• I don’t want to lose the max power of my hardware while writing code, even though it might be 90% it is still only 90%. (Also it doesn't appear that you can use multiple monitors with Parallels or take advantage of both cores in a dual core)
• I don’t want to deal with the fact that I am a .NET consultant and would be walking into clients with a Mac. I am sure most wouldn’t care, but there are a number of people in the MS/.NET camp who would hold it against me. (I know that is a chicken-shit reason, but I make my money billing as a .NET consultant so I have to be mindful of it)

If I start doing more Ruby development, or become focused more on writing or other projects I might pick up a Mac for those purposes, but I won’t be replacing my main .NET development machine anytime soon.

-James

-James