Google patches V1 contain interesting patch to mirror binary log on slave. Although Google is preparing GlobalTransactionId patch, which going to be replacement for MirroredBinlogs, we still think mirroring binary logs is very useful for:
By request of our friends EngineYard we extracted this patch from Google’s patchset and going to include in our next releases. Actually our patch contains features for both MirroredBinlogs and FastMasterPromotion patches, as second provides feature to make slave as master in case of main master failure.
At this moment you can download patch by itself there
with docs on our wiki
Also the patch will be included in OurDelta binaries beside our releases for CentOS / RedHat platform, so you can download and test this feature for your OS.