Google Apps is going to the spotlight as the Los Angeles, CA city commission has decided to move their email system to the cloud-based collaboration software. Microsoft and Google were battling to provide services to the 30,000 city employees. You can read more.
I have compared both services and chosen Google for many users. I even attended a workshop by Microsoft where they pitched the product. The problems were that Microsoft was selling vaporware. Vaporware means that the products did not even exist, yet. The other problem was that Microsoft only offered 1 gigabyte of storage for $10 to $12 per month. Google Apps offered 25 gigabytes of storage for just under $5 per month. It has been an easy decision so far.