Just like any other page on the web, your MySpace profile needs to have some links pointing to it from other sites. For example, http://www.myspace.com/searchrank
currently has 11 links pointing to it from 5 separate web sites - at least according to Yahoo!'s Site Explorer. The sites/pages that are linked to from the profile also register so yes inbound links from a MySpace profile are recognized and counted, if the profile itself has some links pointing to it and is indexed by the search engines.
How much that actually plays into ranking again is like any other page on the Internet in that it will depend on what kind of authority the MySpace profile has in place.
Oh and before it gets asked, the best way to get a MySpace profile indexed (after you create a static URL like the one above) is to link to it from your own site, such as in your "About Us" section (as I did) and then add it to sites like MyBlogLog, Mashable and the like.