This very interesting story is on the official Vietnam Tourism website. It suggests that a number of international bus routes are to be opened between Vietnam and Laos.
The specific routes are:
Kon Tum – Vientiane (already open)
Kon Tum – Champasak (already open)
Kon Tum – Attapue (already open)
Dien Bien Phu – Udomxai
Dien Bien Phu - Luang Prabang
Ha Tinh – Khammuon
Gia Lai – Champasak
Quang Binh – Vientiane
Dak Lak – Vientiane
Dak Lak – Champasak
While there's no information on if all these borders will be open for foreign tourists, it nevertheless sounds very promising -- especially the Dien Bien Phu crossing!
Full story on Vietnam Tourism here.