There is no date for the conference yet, nor has a schedule of what will be shown off. The only response by a Microsoft executive regarding the report was: "We're excited to be back at Gamescom this year but we're not announcing any further details on our plans at this time. Please stay tuned for more details!"
Microsoft has never done a conference at GamesCom before, but it's not surprising that the company is taking a keener interest in Europe, since Phil Harrison, formerly of SCEE, is now Microsoft's corporate VP of its Interactive Entertainment division (read as Xbox and Windows games). Harrison was hired back in March 2012 to "not only lead the Microsoft Studios European organisation directly, but will also influence the broader performance of IEB's European business through strategic partnerships and by bringing culturally relevant entertainment experiences to Microsoft platforms, now and in the future."
In other words, make the Xbox brand more attractive in Europe.
GamesCom 2013 will be in late August, a few months before both the Xbox One and PlayStation 4 launch. It'll be interesting to see what announcements Microsoft will be making so close to release.