extremely, nothing comes remotely close. Pretty much every open source project has at least one channel in
freenode.net, quakenet is very popular with gamers . #python has around 2000 people online at all times, #clojure 700 , #java 466 , #c++ 1000, #emacs 1000, there is even irc channels for computets back from the 80s like my first computer Amstrad CPC 6128 at #cpc etc
Blender which the program I use the most has around 5 channels, Blender also is a bit special in that all the development effort is coordinated via irc meetings usually every Sunday where all main devs are required to attend , moderated by the project leader , and make decisions on how the project should proceed, which features should go in and when the releases should come out. The project leader then publishes the meeting notes on the website which is a summary of the irc chat. There are other projects that follow similar approach to their development too like mypaint and Gimp.