I used to let my students use ipods as long as "I didn't notice them" as
well. It worked well. That is, until one was stolen in the middle of art
class during the clean-up chaos. The girl flipped out, the students
accused each other (because we all knew it was someone currently in the
room), I had to call admin...it was a nightmare. The girl's mother was
livid, my admin was livid...I felt horrible.
It showed up a few days later in a trash can - after the battery had run
out, and the theif realized that it couldn't be recharged w/o the docking
station.
I will never, ever, EVER allow anything like that in my room again. Ever.