Mr. Jeff Lait has finished his yearly analysis of roguelike development activity!

We are doing very well for roguelike creation – five new tracked roguelikes per month, a new peak.  The new Old column, however, I think shows where some of the sense of stasis in the genre comes from.  The early increases may be due to sampling effects as existing roguelikes were largely added to the list.  But for the last three years we’ve seen a balance at about 30 roguelikes being actively worked on.

Check his analysis at this roguetemple article (or the original usenet post (Via google groups))