Windows.Forms is approaching feature completeness in Mono. In the next few weeks we will be doing the first beta release of Mono for our target Mono 1.2.
Although most of the API coverage was done a few months ago, the semantics of it were not exactly perfect. We were lucky to be able to tap into a large body of open source software for Windows.Forms to test and bug fix Mono's implementation.
More recently, as Winforms has become more complete we have started work in running proprietary or commercial applications to run in Mono.
He has blogged a set of screenshots tracking the progress from the December to this date, here are the first and last screenshot from his blog:
Nexxia in December.
Nexxia running on Mono today.
Check out his blog for more information.