I too like the new MSN and think the results are actually better than Google's, however, on my poll at www.search-this.com less than 15% of the people think MSN supplies the best results. 7% for Yahoo and a staggering 74% for Google.
I don't focus on any particular engine when optimizing...It's not like I say, 'oh, I'll add this for Google and toss this in for MSN and then do this for Yahoo.' Rather I just optimize in a general sence...