Comscore released their site information about webmail providers, and the real winner was Yahoo Mail, which not only cemented its lead as the number one webmail provider, but also extended its lead over its rivals. The other big news was the growth of Gmail, which is on a pace to surpass Windows Live/Hotmail by the end of 2009.

Yahoo Mail ended 2008 with 91.9 million users, blowing away Microsoft’s offerings (43.5 million) and Gmail (29.6 million). Yahoo Mail’s finish is particularly impressive when you consider that it extended its lead over Gmail, which continues to generate plenty of press. Yahoo added over 9 million users last year, more than Gmail (which added 8.8 million) and Windows Live/Hotmail (which lost 2.2 million users).

Despite Yahoo’s dominance, Gmail continues to make inroads. It’s pace of growth combined with the drop in Windows Live/Hotmail users could lead to Gmail surpassing Hotmail later this year. Still, they have a mammoth hill to climb to beat Yahoo.

Mail is a good indication of how Yahoo’s content assets are significantly undervalued by the business world. From it’s home page portal to Flickr to Delicious to Yahoo Mail and other brands, Yahoo continues to dominate in important online categories. The real question for Yahoo has always been monetizing these assets effectively, something that is the real source of Yahoo’s problems.