To be quite honest the adcom wasn't that "forthcoming". However, a student host of mine said that in the past, HBS would send out a huge wave at the beg. of R1 and it would quiet down quick before the decision date. This year, the adcom is apparently spreading out the interview invites. I met some impressive folks who had strong profiles and had not yet heard from HBS... I would be surprised if all invites were out.
Another piece of information I got (take it for what it's worth) is that R1 and R2, in terms of chances, are identical. Who knows... From what I gathered, HBS is seeking diversity rather than pure stats (ie GPA/GMAT/WE@ big name firm/bank/consulting,etc.). This was huge for someone like myself in retail/entrepreneurship.