Today the Exchange Team released Rollup 1 for Exchange Server 2010 Service Pack 3 (KB2803727). This update raises Exchange 2010 version number to 126.96.36.199.
As of Service Pack 2 Rollup 4, it’s no longer required to disable/re-enable Forefront Protection for Exchange using the fscutility to be able to install the Rollup properly. However, if you want to remain in control, you can disable Forefront before installing the Rollup using fscutility /disable and re-enable it afterwards using fscutility /enable.
As with any Hotfix, Rollup or Service Pack, I’d recommend to thoroughly test this rollup in a test and acceptance environment first, prior to implementing it in production.
You can download Exchange 2010 SP3 Rollup 1 here.