If a site needs interim reputation levels, that is a strong indication that the site probably wasn't really ready for full status. The question and user counts look good, but users are not voting enough (an important part of participation). You're essentially saying that the site does not have the reputation/experience necessary to take care of itself, yet.
The solution is not to create another set of interim reputation levels:
@rchern: …it would just be yet another beta stage on top of the private and public betas. We don’t need 4 beta stages. If the site is going to graduate, it needs to graduate. Perhaps basing graduation off of number of users at the different rep levels instead of a hard 90 days would be a better indication of a community’s ability to self-police and readiness to be a real site.
I agree. We are taking a closer look at this. Having enough users to properly operate the site is a better measurement of readiness, rather than imposing the hard 90-day limit.