I think it's only appropriate to congratulate the Windows Live Writer team on the release of their Beta by posting this entry using the Windows Live Writer Beta itself.
I've been using their internal release candidates for several weeks, and I have to say, it's the best blog posting tool I've ever used. This was clearly built by folks who know and understand the blogging space intimately -- little surprise, since it's developed by the team that wrote the excellent Onfolio research tool and RSS aggregator that Microsoft acquired earlier this year.
Liveside.net has a great interview with J.J. Allaire, who leads the Writer team.
So, check out their blog to learn all about it at: http://windowslivewriter.spaces.live.com/