CRM 2011 Update Rollup release build numbers, and how to find them

Version Release Date Build Number KB Article
Release Candidate 5.0.9688.53 2461082
Beta (On Premise) 5.0.9585.106
Beta (Online) 5.0.9585.107
RTM February 16, 2011 5.0.9688.583 Download RTM
Update Rollup 1 April 7, 2011 5.0.9688.1045 2466084
Update Rollup 2 June 2, 2011 5.0.9688.1155 2466086
Update Rollup 3 July 28, 2011 5.0.9688.1244 2547347
Update Rollup 4 September 9, 2011 5.0.9688.1450 2556167
Update Rollup 5 October 20, 2011 05.00.9688.1533 2567454
Update Rollup 6 January 12, 2012 5.0.9689.1985