Mem-
I think you and ScubaRon are reading a sentance and interpreting it two different ways. The sentance says scuba tanks can not be checked. You are interpreting it as meaning compressed tanks, and he is interpreting it as saying no tanks, period, end of story.
I am interpreting it as ambiguiosly worded and could lead to unpredictable results by the people doing the screening of your checked luggage.
Also, I'm sure you won't attack me for my lack of airport knowledge considering my background...