To tell you the truth, cheating can be done at any site.
Most sites do monitor players that are suspected cheaters. No site can stop cheating when ever money is involved you will find dishonest people. It would be real easy for me to site at a table with 3 friends and have them on a MSN chat and talk about my cards with them. It is ussally easy to detect this kind of cheating by watching a table before you sit. Tournaments are different due to the random seating so it doesn't happen as much in a tourney.
The reason AP is such a big story is because it was someone who worked at the site that did the cheating. Since AP and Vegas use the same software it could happen at Vegas too.
The story about Vegas was broke by players reporting the cheating. The players or the site will chatch a cheater in the long run. No site wants to be caught cheating like AP did. Most sites are very honest and try hard to catch any kind of cheating and remove the players.