This Business Week article 'Google Steps Into Microsoft's Office' is interesting because it is the first time I have seen a rather large corporate entity (Pixar/Disney) express an interest in moving to a non-Microsoft, Web-based platform like Google Apps for your Domain. The other interesting point to note is published user-base of Microsoft Office Live which is sitting at 250,000 businesses, quite a respectable number for a new, non-free service.
I have been a user of Google Apps for your Domain for a while now on a number of domains and have got a few other well entrenched in-house email fans to sign up as well. By far and away the best things about it has been the spam protection and the fact that within an evening you can have a fully functioning email and calendar service up and running with no fuss at all. It has been slightly disappointing that the applications list has not grown to cover the Docs and Spreadsheets products already and many of the new GMail features such as the very handy retrieve mail service or increased storage sizes have not become available to Apps users sooner.