View the current orderbook.
reddit, github, the wiki for getting started, chat with us on IRC freenode #joinmarket, or cyberguerrilla same channel (bridged).
New joinmarket codebase now fully supports both Makers and Takers, uses segwit-based wallets for lower fees, and has some extra features; start at the README and see some documentation in docs directory. There is a version of Joinmarket-Qt app (see the releases page for latest binary, or use script). Here are some short walkthrough videos, a bit out of date, but may still be useful:
(First and second videos introduce wallet loading and some settings; you can probably skip these, you can also take a look at the old walkthrough; the introductory steps in the walkthrough are still valid (not the installation of course). The third video, on single coinjoins and the fourth, on tumbling are useful for any users, probably.)Blog of Adam Gibson (maintainer of site, Joinmarket contributor).
Currently if you want to use non-segwit/p2sh addresses, i.e. '1' addresses, you can still use the original codebase, version 0.2.3 is latest, as here. The newest segwit version (i.e. using '3' addresses) is as mentioned in the previous paragraph, v0.3.2. It'll be best if people migrate to that as soon as it makes sense for them (the more of us use segwit the better for the whole system).
Ongoing discussion of a likely future protocol update here; we are looking for a good way to make economical Sybilling ineffective. There are some promising directions. Please get involved!
Another interesting project is for Coinswap instead of Coinjoin, see here.