I did the affiliate registration prior to CafePress' switch to Commission Junction. Is that old affiliate ID gone? Do I need to re-register with CJ now?

Thanks!

Yes, I suggest you register with commission junction and then apply to the program through cj.

you can still use the old affiliate program link formats and affiliate id (now called your account id), however, it is a beter practice to use the cj formated links and ids.

happy affiliating!