Microsoft’s (Nasdaq: MSFT) Hotmail has about as many users as the Earth has Americans, but recently the company noticed that the service’s design and feature set was beginning to look pretty stale. Some of its features actually hadn’t been touched in years, and in that time, rival services like Yahoo (Nasdaq: YHOO) and Gmail have been continuously revamping their message centers, and their user volumes have grown accordingly, especially Google’s.

So this summer, Hotmailers will get all sorts of new toys. There’ll be a new sorting feature and a window for sending status updates directly from the email app. You’ll get new ways to clean up the inbox, including ways to automatically delete marketing items that aren’t spam but are still stuff you don’t want to read.

Then there’s this thing called “Active View.” If you get an email with a bunch of photos in it, you can automatically view them as a slideshow instead of downloading them via the browser. Silverlight required.

Hotmail will also have access to Skydrive, where you’ll be able to store documents. Skydrive will also let you send massive photo sets — up to 200 — by uploading them to Skydrive and then sending a link.