Looks amazing Tree!
A couple thoughts -
Your new weather icons that you created a few days back, they are beautiful. Why did you decide not to use them in Lightbox?
Are you planning support for some of the common addons, like Weather+, Artwork Downloader, TVTunes, Artist Slideshow, Metadata Actors, Random Items, etc?
How much "customize-ability" are you planning for the tiles for each section? Will you allow for users to configure the tiles on the left to show things like Recently Added, Featured, Genre's, Years, etc (I know I saw genres)?
Planning on extrafanart support? This would be amazing combined with a Zune-like slideshow for Music!
Also - congrats on joining the XBMC Team