Ouch. It looks like there are two different Arduino Mini Pro’s around – a 5V @ 16 MHz and a 3.3V @ 8 MHz version. I thought I had the latter, but a quick check tells me otherwise. Which is no good when you’re trying to hook up 3.3V modules that do not tolerate 5V levels!
Oh well, just order the right one and wait for it to arrive…
Meanwhile, here’s another kind of impedance mismatch:
The obnoxious 2 mm vs. 2.54 mm pinout. Yuck.