i dropped my phone hard a week or so ago and was trying to find the same answer.
yeah anything that does an enter will take a picture.
keypad. center button. pressing down on the scroll wheel. all will take a picture.
I wonder what it is about that button that makes it so "fragile"
I basically, not literlly, threw my phone at concrete... it scuffed and the camera button broke. Internal speaker wire came undone as well.
had to void the warrenty to open it up and fix it but i was amazed at the phones durability at least externally.
now if only the software was as solid.