I know some people have asked in the past how to map latitude/longitude on Live Maps and I just ran into a scenario where I needed to do it. Well, it's as simple as typing in the desired lat/long, selecting Locations, and doing a search. Admittedly, it's not the most intuitive thing in the world, but I figured it out in a matter of seconds.
If you're looking to link directly to a lat/long position, you can also pass in the lat/long via querystring parameters. There are a number of different querystring parameters, and I'm not going to go thru them all here, but I will mention the two most important: cp and where1. The cp parameter is the lat/long position you want to center on. Using this alone will center on the lat/long at the default level, which isn't much help. For this reason, I'd recommend you also specify the where1 parameter, which performs a search for the lat/long. The key thing to remember here is that cp delimits the latitude and longitude by a tilde (~), whereas where1 uses a comma. Here's a sample URL: http://maps.live.com?cp=36.16773~-115.157181&where1=36.16783%2C-115.15707.