Team Fortress 2's long awaited Mann vs. Machine update launched yesterday and so far it's been a mixed bag. As Mike Fahey mentioned earlier today, matchmaking is an unplayable mess, due to the sheer demand and a lack of community servers. Hopefully that will be resolved in the coming days, but in the meantime you can still play the mode directly, using the server list.
Kinja is in read-only mode. We are working to restore service.