Last week, Microsoft published Rollup 1 for Microsoft CRM 2013.
Starting with CRM 2013, The rollup number is included within the build number. Rollup 1 is published as 6.0.0001.0061
Update Rollup 1 contains stability and memory-consumption improvements as well as bug fixes.
We maintain a list of all rollups on our Microsoft CRM 2013 Resources page.