We knew this was coming, and Microsoft didn’t take long to make it happen. The first Desktop App has appeared in the Store, and it is Microsoft Office 2010! Yes, you can find it under Productivity Category. Go check it out and install it if you must.
But Microsoft, you promised us Office15 Preview in June, do we have to wait really long for it? :)
[Update] If you can’t see it in the Productivity Category, open up the Search Charm and search for Office.