This is working for me (today). I'd like to see if it helps anyone else. I'm using Logic 9 on an Intel w/Snow Leopard. I have a slave G5 over ethernet running VEP server. Play seems to work completely normally if I do the following. Someone else try and report back...
1) Quit all apps (especially VEP Server... won't work if you don't)
2) Start your host sequencer
3) Open a new session and open an instance of Play on a new track.
4) Close the session (you don't have to load anything into Play)
5) Start VEP Server outside your host
6) Open a new (or existing) session in your host sequencer.
7) Work away!
It seems for some reason (some people have mentioned memory issues) that if I open an instance of Play in an empty session before I open my real session things seem to be ok. Maybe Play needs to grab some chunk of memory first and simply opening the plug in does that? Just came across this today after some experimenting, and so far so good, I'll report any further complications or if it's continually working. Meanwhile give it a go and let us know your setup and if it worked or not...