I am willing to "bid" on this project as well if it's still available.
All i did was freelancing and if pmed i can give you a list of websites were i have been working.
I am planning to code your project in php, but also to take advantage of the jquery jsonp (cross domain json) and my own framework.
I don't want to use any existing open source forum, and i plan to use my framework because i will code into it only what is required for the project, without any extra functions.
I could code the project and also think it's arhitecture, something designed for future use, for cluster (as you probably noticed, bitcoins will attract more and more visitors), and probably in future you will have to move to a cluster.
Planning to use a mysql cluster with a http cluster (separating the mysql from http, to ensure a minimum load on the server side).
Everything you requested will be implemented and i will be using my framework with or without smarty integrated (as you wish).
Something else will be added at the security, because of the jsonp cluster a token will be created to monitor visitors.
Another key factor is that i will code a module to detect xss or sql attacks and to be tracked down to ip, banning it for a limited time if detected and mailing admins/dev crew.
The design will be unique, and will try to make it clean, but again, we will take advantage of technology such as canvas/css 3/jquery effects.
Because i plan to use something unique/new (jquery for the http cluster) wich will improve the costs and the ressources of the server and that i am going to take advantage of the latest technology and methods that are available (without the use of plugins, just native codes) i will have to ask abit more than it's offered, 3600 BTC.
Example of my framework implemented into a game(not fully developed): http://code.google.com/p/v2ge/source/browse/#svn%2Ftrunk%2FV2GE
Let me know if you are interested in my offer and send me a pm.