Update: As Shane pointed out to me you can simply use the native Facebook app to do Facebook chat for free though I still want to see a Google Talk client come out officially. (Better yet Google Maps!)
I am waiting for Google or RIM to release their own Google Talk client for the PlayBook. If you are tired of waiting and using the web clients you may want to check out Scott Greenberg Design’s new Client for Google Talk and Client for Facebook Chat. They seem pretty bare bones but functional. The Facebook chat client has been out since mid-November but Thom let me know that the Google Talk client just launched. Either way they are unofficial clients so buyer beware.
If you want you can check them out in App World: