One other thing I forgot is that some betas only have changes that affect a few people - like when they fix something with a particular interface or add particular features. I think when those things are something they want to release they like to have a few people who it affects do and then report back.
I do think AC's next release to more betas/regular release is slated for the near future as they keep talking about imminent release.
In regards to 'hot fixes' I know it is not the same but in the ealy years if an error or something was found and we sent e-mail to Jon he would try to incremental release quickly - he said that became problematic as he would be guilty of 'feature creep' or trying to release new version for one new, neat feature and that may end up affecting a lot.
When the jump went from Version 4 to 5 it was a big jump adding in the CCHIT certification stuff and when it jumped again to Version 6 it was another big leasp.
