Throw some new tallies on both sides of the 'Arrested Development' season 4 board? Last night, the once and future 'Arrested Development' star Will Arnett dropped by 'Conan' in promotion of NBC's 'Up All Night,' but couldn't resist sharing a few secrets of the upcoming 'Arrested Development' reunion, particularly with two of his cast-mates sitting beside him! That's right, not only will Andy Richter return for the revival, but his late night boss Conan O'Brien will put in an appearance as well!

'Arrested Development' season 4 may have picked itself another new guest star, but it also gained a whole lot of Andy Richter. The news broke last night when 'Arrested' star Will Arnett put in an appearance on 'Conan,' hinting both at co-host Andy Richter's return to the 2013 Netflix revival, as well as a role for Conan O'Brien himself.

Fans of the series will remember that Richter put in several appearances not only as himself, but also portraying his four (fictional) twin brothers Donnie, Emmett, Chareth and Rocky. Presumably, Conan O'Brien would play himself alongside Richter, but we'll find out for sure next year.

Richter and O'Brien are the latest addition to a star-studded reunion season that features appearances from ‘Parks and Recreation's’ Ben Schwartz, ‘Up All Night’s’ Chris Diamantopoulos, all three stars of Comedy Central’s ‘Workaholics,’ Mad Men’s’ John Slattery, Isla Fisher and Terry Crews, as well as returning series players Carl Weathers, Jeff Garlin, Liza Minnelli, Judy Greer, Henry Winkler and Scott Baio.

Check out the clip of Arnett's announcement below, and tell us what you want from 'Arrested Development' season 4 in the comments!

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