This is what I mean: http://www.neowin.net/news/microsoft-explains-why-outlookcom...
With Google Apps you just turn it on... and can force users to use it.
Office 365 and stand alone (ie: private) exchange installs certainly support it.
Comparing outlook.com to 'Microsoft Exchange' (whether you're talking about Office 365 which is MS's 'cloud' solution, or private Exchange servers) is not exactly fair. One is designed as a free email hosting solution for personal use (essentially replacing Hotmail), the other is designed for business/organizational use and costs money.