Jay Pipes is not only checking in the code, but giving an excellent series of posts on how it works starting with this one:
Drizzle Replication – The Command Message – Jay Pipes.
I’ve been using replication for HA and scaling since 3.23 and IMHO it is *the* killer feature of mysql. Drizzle getting this right is crucial for me as a user, and while I’m not C/C++ developer it really looks like Jay is doing quality careful engineering.