Originally, the UFC hoped to hold a show in Boston in November of this year. However, they were unable to get regulated in time, and it looks like they may be heading back to Montreal instead:
The UFC is looking to return to Canada later this year...
White said the mixed martial arts organization hopes to return in November or December.
They already have the TUF finale and their annual Las Vegas show at the end of December, so I suspect it would be for November if they get it done, possibly with St. Pierre vs. Penn on top.