I have the original Galaxy Tab 3G on Bell in Canada. So far, no wifi keys have been stored. I also have a Coby Kyros and a Witstech A81E. Those two have been flashed with custom roms many times and I have always had to retype my wifi key.

Maybe it depends on carrier and country?

Good discussion. I had better be good. Between my iPhone and my Android Tabs, i have nowhere to hide!