Wow, so many answers
I have now a solution for my problem and this solution dont need any Bonjour ...
The Key is to use a multicast DNS - I simply broadcast to 126.96.36.199:5353 (one-shot-queries) using ANY / PTR and listen to the answers. I get the IPs of all devices that implements the service I'm looking for (for example _daap._tcp.local) plus my own IP as an echo.
I think this is a best and simplest solution for WinRT - you can wait many time for an Bonjour's implementation as I see