Sure is - http://www.tatnews.org/latest_update/detail.asp?id=2151#2 offers fairly up to date information. Visa-On-Arrival going into Laos is not accommodated by the International Bus at all. They will deny you boarding at the Udon Thani bus station, so you must have a Visa ahead of time. One way round this is a bit tangental. The bus which goes to the border from the Udon Thani airport (the morning one connects with the arrival of the Air Asia flight (arrival approx 0825) goes to the border where you are able to do Visa-On-Arrival. You then have to get from the Friendship Bridge border area to downtown Vientiane under your own steam; it is more expensive, but solves the problem.
Hope that helps about 7 years ago