A lot of talk has been present about Microsoft being in third place overall (market share, apps, developers etc. combined), attempting to catch Apple and Google. A recent survey released by IDC shows a trend for the mobile OS group with developer interest throughout 2010/11 - Microsoft is yet again third.
Although we are ahead of RIM at the last point, we should put away the celebration packs of goodies due to the interest percentage for WP7 falling below what the platform had this time last year. Blackberry suffered a heavier fall and thus WP7 comes out tops, notably due to the Nokia partnership (which will hopefully boost developer interest once they bring handsets to the table).
Also included in the report is a fragmentation chart displaying what developers are most concerned with. Android is a known pray to OS and hardware fragmentation, something which WP7 hasn't had (yet, I've touched wood). The most concern is reportedly skill fragmentation, however.
So overall, WP7 is still playing the slow catchup and I doubt anything will alter until Nokia devices come into the spotlight, or a good number of contracts end soon and customers wish to go to WP7.