There are quite a few reported cases every year from what I understand, although no one is really studying it so it would be hard to say for sure. I believe CDC said there were 40,000 reported cases of salmonella but I don't know if that is just due to reptiles or from all sources. CDC also guesstimated that there are actually closer to 90,000 cases including the unreported cases. I did see these figures in HSUS newsletter about banning reptiles as pets, so the figures could be exaggerated. It seems like a lot to me.
That being said, I have heard that husbandry is directly related to the risk of salmonella. If you are keeping your cages clean, quaranting new animals, washing your hands and taking your herps to a vet for yearly health/fecal exams I would say you have less of a risk. I don't let mine in bed with me, but they do crawl around on the couch since I normally don't put the couch in my mouth. Also I wouldn't directly lick the snakes if I were you... 
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Anna Plaxco
Corns
1.0 Snow - Cornelius
1.1 Ghost (pastel) - Eek & Boo
1.1 Amel - ? & Scarlet
0.1 Hypo - Nikko
0.1 Anery - Missy
0.1 Hypo Hurricane Motley - Dot
Boas
0.1 Columbian - Bella
Lizards
0.0.1 Leopard Gecko - Leo
Rats
0.1 Dumbo - Dirt
Cats
1.1 Siamese - Blue & Fiona
0.1 Grey - Dru
Horses
1.0 Thourghbred (Hunter/Jumper) - Morgan's Majesty aka Cody
-We have no right to distress any of God's creatures without a very good reason; we call them dumb animals, and so they are for they cannot tell us how they feel; but they do not suffer less because they have no words. -Anna Sewell