People saying March 1st more or less nailed it.
For anyone that's unsure of what that is, basically free agents signed by teams this season can't be traded until then.
As far as I understand it, it's not necessarily March 1st, but it's the free agents being on a team for a length of time. In a normal season, this certain date would have already passed. Because of the lockout, the date got pushed ahead, and just happens to be March 1st.
So pretty much, anyone itching to hear some real trade rumors pretty much should mark that date on their calendar.