Short answer: YES
I was having trouble with "onvalidation" ... the code didn't seem to be running. So I was going to ask if SQLFORM supported it ... but [blush] when preparing my question, I realized I had set the option on the wrong form. (I have a ping-pong pair of forms ... you enter data for table A in one form, are redirected to the form for table B, which then redirects back to the A form. The validation is needed for B, and I had set the option in the other form.
I'm kind of surprised that didn't cause a ticket, because the validation code was asking for a form.vars.b_of_B that wasn't part of A's form.vars.
Anyway, just another example of trying to blame Web2py when the error was between keyboard and chair.