From the MBP in OSX? Not gonna happen without a transcoding dlna/upnp server, like ps3mediaserver. But then what's the point if your interest is 1080p? Quality will suffer tremendously.
If you run something like windows 7 within bootcamp, then maybe using the media center extender so long as you have an appropriate mkv splitter, like haali, installed. Even then, if your mkvs have dts audio tracks, don't count on sound working. And video quality will still suck in any case.
Until MS programs in native mkv support, it's just going to be more hassle than it's worth with the 360.
I suggest something like a WDTV live instead.