Today Microsoft announced the official launch of three Windows Live services, Live.com, Windows Live Search, and Windows Live Mobile.
Windows Live Search, will by Thursday become the search engine for MSN, according to Ken Moss in the Live Search blog on Spaces. Ken gives a nice overview of what to expect from Live Search:

What’s new in Live Search:

• A clean, custom interface - The new interface updates not only the colors and fonts of the service, but the design and layout as well. The new scope bar enables you to see search results from the Web, images, local maps/directions, videos, etc without having to re-enter your query in the search box. The scope bar remembers your most recent scopes like Video or Academic so your search experience will feel very personalized.
• Related Searches help you refine your query by simply clicking on a list of related terms (try Jaguar, Las Vegas, CSI). We’ve found that helping our customers refine their queries is one of the biggest things we can do to help people find their answers.
• Image Search delivers a new rich experience tailored for the task of searching for pictures. It includes: Smart Scroll, which gets rid of pagination; meta data surfaced by hovering over an image vs. having words clutter up your results; dynamic image resizing; related people lists that are addictive (try Oprah Winfrey, Katharine McPhee, Tom Hanks); and lastly a scratch pad for images since we know most people searching on images want access to multiple images and this is a quick and easy way to save your results to access them later.
• Local Search is getting more robust everyday and this release provides new or updated imagery for 25 U.S. cities, meaning we are covering about 30% of the U.S. population now. There are also some new additions to collections and access to White Pages data. Check out the service or check out the blog for more details.
• Live QnA beta makes its full public debut! We’ve been out for a bit now but are now baked into the search scope bar and are no longer in a closed beta. We are excited about this vertical because it can bring the community into your search experience; if Web search doesn’t answer your questions right away, get the answer from real people! Live QnA is particularly powerful due to its tight integration with other Live social services, like Windows Live Messenger and Windows Live Spaces.
• Video Search beta can be found here or under the “More” tab in the scope bar along with a host of other beta verticals like Academic and Product Search as well as links to Live Macros where you effectively create your own search engine, or browse ones created by others in the community (try a macro I created for my hobby Poker – try searching for “Phil”).

Live.com, while it released it's latest update last week, went legit as well, and we'll bring you more on the new features of Live Mobile tomorrow.

Here's the Microsoft press release:

Link to Windows Live Services Reach Key Milestones