A month ago we began working with Microsoft Online Services. It has gone better than expected and we are now accelerating our deployment of Microsoft Online Services, having achieved positive feedback from users.
The biggest uptake has been Exchange Online, especially with organisations that have multiple branches and/or a distributed workforce.
One of the more interesting projects that we have on the go is improving email efficiency for a business that was created as a result of combining four firms (each in different cities), using a total of six systems to manage and deliver email. Moving to Microsoft Exchange Online is not only going to save them on hardware and licensing (something they needed to do, due to the age of the systems), but operational costs are also going to fall due to us being able to eliminate five systems that previously required support, licensing, and management.
See the cost estimator here for how cost effective this solution can be.