Andrew loves for people to develope patches, you might search the forums for patches that have not been created, as of yet...
2 major issues are remaining: Antivirus/spam and administration. I suspect the first is the easiest to tackle with the least amount of ramp up. JASON is probably our first target. And it looks like creating a plugin is easy. The worst thing is that it will suck for memory utilization but that is fine for 1.0 and for an ancillary component. It should be a mail listener and probably on another queue.
As for the release schedule/date, there will be an announcement regarding this next week.