Exchange Team Blog released new version of Update Rollup 8 for Exchange 2010 SP3.
You can download it here:
Update Rollup 8 For Exchange 2010 SP3 (KB2986475)
When you install this update your system version will change to: 18.104.22.168
All informations about changes included in RU 8 for Exchange 2010 SP3 can be found here: KB2986475