Sure does look like it. I came up with the following clues that register.com might now be running as a Enom reseller.
New Layout on behalf of register.com
They used to offer some obscure cctld's, which I do not see offered anymore.
Last time I remember, it seems like there were ~8 million domain names at Enom (top of page network domain counter), now there seems to be almost 9 million.
According to webhosting.info(as of 12/11/06), it looks like between Enom Statistics and Bulk Register Statistics, there are 7,191,858 Domain Names between them. Subtract the current total (remember there is a difference of ~6 days as well) that Enom shows on their homepage (which is 8,720,124) and you get 1,528,266, which indeed could be the 2/3 of the register.com database.
The numbers don't match up, according to the register.com statistics, but maybe something is in the works.