I don't believe Operation Raincheck is still being used anymore.
Might be a local thing; it's still alive and well (fills up quickly, last I saw) here at ZKC in Olathe, Kansas.
In fact, when I inquired about organizing a customized tour for a VATSIM get together (e.g. more time at the enroute sims

), it seemed like they were more than happy to talk about scheduling something.
EDIT: Okay, perhaps not "well"... either I can't search properly, or they haven't announced any upcoming instances of the event.