Their free online machine translation engine MicrosoftTranslator.com "makes the Web more worldly" (source) and it's also the "Free online translation service for a truly world-wide web".
Oh, come on!
First of all Microsoft Translator supports much fewer language pairs than Google Translate.
Secondly, in Microsoft Translator there's a restriction for the text that you can translate (up to 500 words) and in Google Translate there isn't.
Thirdly, claiming the "truly world-wide web" is outrageous when Microsoft are so far behind according to the first two criteria!
Anyway, Microsoft have invested a lot of time and efforts in their machine translation research and their product blog "Microsoft Research Machine Translation (MSR-MT) Team Blog" is definitely worth seeing. I guess that the healthy competition coming from Google will urge them to expand their service even more in the future.