It looks like Microsoft and Nokia are up for a party. Get prepared for little announcement for August 17, 2011. Both companies sent out an invitation for a joint-event at this month’s GamesCom in Cologne, Germany, according to the unwired.

Nokia’s first Windows phone, codenamed Sea Ray, looks nearly identical to the recently-announced Meego-based N9 smartphone, but it’s running Microsoft’s Windows Phone operating system. Nokia’s first Windows Phone 7 handset(s) will be launching in Europe later this year: France, Germany, UK, Spain, Italy, and the Netherlands have been confirmed.

The invitation tells attendees “exciting actions and surprises will make it an evening to remember.” Nokia and Microsoft will raffle 3 Nokia (phones) with Windows Phone (as soon as available) so it sounds like the 17th could be the official announcement date but not the sales start of Nokia’s first Windows Phone 7 smartphone.

UPDATE: As per Engadget, Nokia claims the event to be “local developer event,” and to not expect any new devices that we haven’t heard of before.