I only discovered ACT in 2004, (although I believe I had previously been heavily influenced by the 1996 JCCP paper on emotional avoidance). I began reading furiously, and have since attended:
a 4 day work shop with Robyn Walser
2 day "advanced" workshop with Kelly Wilson
the 2005 ACT Summer Institute
4 day workshp with Gerog Eifert and John Forsyth on ACT with Anxiety
I am also involved in an ACT interest/education group that meets roughly every two weeks locally