Coderpunks were a group of people who split off from the cypherpunks mailing list in the mid-90s because they felt that the current list was being overwhelmed by spam, paranoid nutcases, and people who just wanted to talk, not actually do anything about the problems facing the goal of having strong, free crypto for everyone, such as the NSA pulling the State Department's strings to control the munitions export rules, the Clipper Chip, the DMCA, and the various legal, illegal, or extra-legal methods the feds use/used to keep crypto out of widespread public use for as long as possible.
So, in theory at least, the coderpunks list was for people who were actually actively writing crypto code, thought that wasn't always the case.
The coderpunks lists died early in 2002, for reasons that have not really been explained too well, but probably having something to do with the time and machine resources needed, acrimony about spam towards the list maintainer (he refused to set up blocks, and the list was hosted on John Gilmore's famous open relay). By now (June 2003), most of the slack has been taken up by various other crypto mailing lists.
Before it's untimely demise, coderpunks was the host for discussions on protocol design, new algorithms, analysis, and perhaps a little more politics than was really necessary.
As far as I am aware, there are still monthly Coderpunks meetings in the San Francisco Bay area.