Based on prior updates by Google of PR this is a rough schedule of updates for 2010.

This would mean an update might be coming this week.

December 31, 2009 – January 1, 2010
March 31, – April 1, 2010
June 31, 2010 – July 1, 2010
December 31, 2010 – January 1, 2011

Data From: GeekyFaust.info