Supybot is actively developed.
In the nearly three years that Supybot has been developed, we've made 36 releases, averaging more than one release per month. Granted, some of these releases were relatively minor updates, but Supybot is very definitely actively developed. Before switching to a Darcs there were more than 6,000 revisions in our CVS repository.
Here are some statistics about other projects:
Eggdrop has made 5 releases since development began on Supybot, the most recent of which was in August of 2004.
Blootbot hasn't made a release since a year before development even began on Supybot.
Infobot hasn't made a release since a year and a half before development began on Supybot.
mozbot hasn't been released or its website even updated since development began on Supybot.
kibot hasn't seen a release or a website update for almost a year and a half.
We could continue this parade of dead or dying projects, but what would be the point? What we're more curious about is, "Are there any IRC bot projects as active as Supybot? Are there any even in the same ballpark?"
Thus far, the answer seems to be "No."