Hotmail will start populating itself with mail from the external accounts. From Microsoft's standpoint, this can get people who are too set on using their current e-mail provider to give Hotmail a try without feeling a jolt of e-mail culture shock. Secondly, it could get people who stopped using Hotmail to come back. There are plenty of reasons why someone would want to condense their e-mail services. Finally, Hotmail brings it all together by syncing your Calender and Contacts from multiple accounts and services and keeping you up to date on external services like Flickr, YouTube, Facebook and more - and sorting it for you. Mesh and Skydrive leave you with nearly no excuse to not have the files you need or having the Office applications to run or edit them.
The social life of Messenger has become extensively robust - even including a free HD video service that rivals Skype and puts Google's video chat to shame. Just as the suite of free software packed in the set of Windows Live Essentials has become better and better over time, so too has the feature set of the Windows Live service.