I've flown with mine a couple of times now. I have the wallet/knife combo. I slide a hundred dollar bill under the clip before getting to the check point and drop the whole wallet in the basket with my keys and change.
In both cases, they took a pen and lifted the wallet (like it was infected) to look at the keys under it).
Once, the gentleman told me I didn't need to put my wallet in the basket as the machine would not effect my credit cards. I just told him I was old fashioned and felt better doing it that way and he just smiled and waved me on through.
John