Is there a PTT specifically for Blackberry based on Pin#s from blackberries?
Nothing carrier specific, along the lines of BB messenger?

I know HipVoice has a prototype soon coming (if not out now), but it has a fee of $10 per month. What I had in mind is free (one time software purchase).
I did some searching but couldn't find any futher info....

If not, it would be nice...

I have not seen a free app that does what you are looking for. I have had the opportunity to use the HipVoice application, and it is worth the $10 per month to have carrier independent PT. I would recommend you check it out once it is released to the public.

anyone try it with good/bad reviews?

Are you asking about HipVoice? If you are, I have been using it for the last few months through the closed beta, and it has been very good.