The problem with replication is that we have so many things that we want to do, but we are not that many people. What we do is what everybody does when the to-do list is to long: prioritize. Since the replication features are developed for you (yes, you), we have added a quickpoll on the http://dev.mysql.com/ where you can pick the three most important replication features that you would like to see us focus on next (after the 5.1 GA).
Do you think that on-line checks for table consistency is for weenies that cannot write a simple little script to do that? Please tell us that.
Do you prefer to live on the edge and think that semi-synchronous replication is for safety junkies? Well, we'll be glad to hear your opinion.
Do you think that the YouTube oracle algorithm hack is the coolest thing on earth and that we should make sure to have it in a release soon? In this case you should especially tell me, because I think it is a pretty cool idea as well.
We cannot promise that they will be done, and there are some features on the list that requires a substantial amount of work, so it might be that we decide to deliver many small features rather than one big feature... but we need your input, so please go and take the quickpoll on http://dev.mysql.com/, because you can be part of making MySQL the best on-line database for modern applications in the world.