Thomas: The closest I can think of offhand in a free quality way that you can get at the moment is segoepr.ttf (looks quite a lot like an italic comic sans) Back in 2007 Microsoft accidentally leaked a PDF called "Print Ad for Microsoft Dynamics Business Management Solutions Brief Description". It contained the complete Segoe collection. The pdf is no longer available, but people mirrored the fonts installed, and you can still find them as a result.
Incidentally, the collection includes a semi-bold weight.