It's a trap!

M. David Peterson theorizes that competitivness is behind MSFTs offer to help mozzila.org port Firefox to Vista:

"..MSFT doesn’t like to be outdone by ANYONE.."

Hmm, that doesn't explain the last five years. My theory: they want to lure the FF developers up to Redmond in the winter and dampen thier spirits in the cold, grey, rain so the IE team can catch up. That'll give the IE folks time to implement Javascript 1.7, more CSS, native svg and xaml. And they can steal e4(x)linq from the vb.net folks while they're at it ;-)