I've just read on Planet Debian the Scott James Remnant post about Ubuntu and Debian and I have to agree with him in that the release model they've chosen is a good one; in fact, very similar models have been proposed for Debian on different CDD meetings (see New way to distribute Debian). The good thing about Ubuntu is that it has the people to make this model a big success.
I hope that after the Sarge release we will open a Debian release model discussion, because the current model is not the best one and changing it can be very good for the distribution as a whole.
I don't know which model is best, but time-based releases are working well for a lot of Free Software Projects. A good release cycle could be once a year, with 10 months of development and 2 of testing, the problem then would probably be the security support, but if we only support 2 releases it will probably be acceptable.
