The current release cycle is WordPress 3.6. It is led by Mark Jaquith, with support from Aaron Campbell.
The focus of this release cycle is Content. You can check out the 3.6 Project Schedule.
This release has seen the core team broken down into Features teams. Each team has a lead, and specific office hours.
Lead: Peter Westwood (Westi)
Backup: Erick Hitter (ethitter)
IRC Hours: Monday at 1600 UTC & Thursday at 1500 UTC
Lead: Andrew Ozz (azaozz)
Backup: Mike Schroder (DH_Shredder)
IRC Hours: Tuesday & Friday at 2100 UTC
Lead: Helen Hou-Sandi (Helen)
Backup: Scott Taylor
IRC Hours: Monday at 1900 UTC & Thursday at 1600 UTC
Lead: Dave Martin
Backup: Drew Jaynes (DrewAPicture)
IRC Hours: Monday & Thursday at 2000 UTC
Lead: Lance Willett
Backup: Konstantin Obenland
IRC Hours: Tuesday & Thursday at 1700 UTC
Maintenance & Bug Gardening
Lead: Sergey Biryukov
Note: IRC Hours are held in #WordPress-dev on irc.freenode.net.