The Live Search URL Submission form was down for almost one month. But, now it is back at http://search.msn.com/docs/submit.aspx, where one submit URLs.
Report of the form being down was reported for the first time at a thread titled, "MSN Submit Down Again" at WebmasterWorld.
The form remained down until in a different WebmasterWorld thread named "Where Can We Submit To MSN Now?", it was written:
"Our URL submission page is still http://search.msn.com/docs/submit.aspx"
Microsoft fixed the URL submission form. But the question is that how often a search engine uses the URLs they obtain from a URL submission form to find new pages. The form was down at MSN for about a month, and it can put some light on this issue. However, the best way to make any search engine find your pages is definitely through links on pages that they have already indexed.