Nessus continues to be a very popular vulnerability scanning option after moving down the proprietary path. The latest release is 4.2 and it is now using a client / server model that has the client being a flash based web client. It is a good move, as I always found the client to be clunky and memory hungry, now its all on the server.
With the final release of Back-Track 4.0, an excellent guide has been written over at linux-tip.net for combining the two.
