its a known issue, they are working on it. I think it had something to do with being compatible with 1.6(no push notification support)
Many here may not have known or used WWF on iphone, but I used it from day one. WWF was very buggy on iPhone (way worse then it is now). The servers would get all jacked up, and it would take hours sometimes for a game move. Making it cross platform also brought up a new set of challenges for them.
Your best bet is just deal with it for now and wait, or use a different word game. It will get better though.