Do it all the time on my mountain bike here in Seattle. I've tried it a couple times on my KLR. Really not that hard. Just like shooting up a steep embankment. Down will rattle your fillings. Up just takes a bit of conviction. As the others have said, just watch your break-over height at the top. A little extra throttle to clear the front wheel helps. The first time you do it will freak you out. After that you realize it's so easy you start looking for reasons. BTW, traffic cops frown on it as a way to circumvent rush hour traffic.
"Yes. It looks insubordinate, but it isn't really." - T.E. Lawrence