For any interested contributors, the deadline for nominations to the Ubuntu Developer Membership Board has been extended by two weeks in hopes of getting more nominations. It wasn't said how many they received during the initial period, but it was at least less than the three being vacated with their two-year terms expiring.
The Developer Membership Board is responsible for reviewing and approving new Ubuntu developers. DMB board members are expected to be Ubuntu developers themselves.
Those interested can find more details on this extended DMB nomination period via ubuntu-devel-announce.