if possible/legal would be ace to have an in-game vent interface which would run the vent program off the users hard disk as usual but relay into a clean and userfriendly in-game gui. if already posted somewhere, would be great to have a link and i can remove this thread ! :)

Not possible. Addons have no ability to interact with programs outside WoW, and the tools (API) available to addons in game aren't sufficient to re-create such a program as Ventrilo. You have the in game voice chat as an option, or using something like a G15 keyboard which has a display that Vent can relay through.

http://www.voice-overlay.info.ms/