GAE gives me fractional sections all the time when i convert to strings (to say pass as a URL parameter to query for the next section of the results). turns out that GAE stores fractional sections in the DB, and an accurate query would include them. i have worked around it satisfactorily for now, but i certianly wouldn't mind if web2py datetime validators dealt with fractional seconds. if needed for backward compatibility i'm fine with specifying an optional parameter that says "yes do parse this datetime that looks like '2011-12-31 13:01:43.453'"
just my 3 cents.... (and i haven't looked at the patch.
