It does not seem odd at all to me that Microsoft would offer a helping hand to Firefox development to get it running on Vista. It makes perfect sense that Microsoft would want to actively engage with this project, for two reasons I can see:
For one, let’s look at the amount of effort Microsoft has placed into developing IE7 to make it more secure, more standards-compliant, and more useable. Good for them! I’ve played with the beta and it is a huge improvement over the existing IE6 implementation.
But with all that effort, it puts IE7 in my opinion just under where Firefox is currently at in terms of overall quality. Not all the bugs with CSS and such have been completely worked out (though most have been) and it’s not quite as useable (though that’s improved a lot too). I’m betting the budget to get Firefox where it is has been considerably smaller. And on top of all that, Firefox is just about to go to the next major milestone of 2.0. Finally, with any darling open-source project, there are more eyes looking at it for bug fixes, for enhancements, and most of all, for security patches. More eyes are looking at Firefox and more hands are writing code for it than Microsoft could ever hope to afford. So while in the short term Microsoft’s browser dominance still reigns, Firefox now has an important chunk of that market share, and it’s increasing over time. Eventually, well-adopted open-source projects will tend to prevail over proprietary software.
Another reason, perhaps more short term thinking, is the buzz about how Microsoft may be trawling for talent. And why not? Apple hired Dave Hyatt, and that was a good thing for Apple as well as for their consumer base. IE could certainly use a little Mozilla in it’s blood.