I usually do a lobby every other time I get on Xbox Live, for the PS3 Users, your not so lucky.
I will update this thread every time I will be doing a lobby, but there is not usually a set schedule, so you will have to check this daily, if not hourly. I mostly do infection lobbies such as Slow-Mo or SuperSpeed. Every week or so I do a 10th Prestige lobby, so keep up with the updates!!!