The last episode in this first half of South Park Season 11 will be Episode 1107, Night of the Living Homeless. The following's from the press release for the episode from Comedy Central:

Increasing numbers of homeless are eating, sleeping and asking for change all over South Park. While the adults are working on creative solutions to care for the homeless, the boys are busy solving the problem once and for all.

This episode will be first shown this Wednesday April 18th at 10 PM (ET/PT) on Comedy Central. Episode-related stuff to follow soon after.