How can I get a screenshot of what's on my AppleTV?
After some quick Googling I found these steps:


Jailbreak
Install aTV Flash (black)
Install nitoTV
Install 'screencapture' (through nitoTV)
SSH in: ssh root@Apple-TV.local (or ssh root@ipaddress, e.g. ssh root@192.168.3.61)
At this point typing in screencapture SHOULD save Screenshot.png to root. If it does not you may need to change ownership on root via: chown mobile:staff ./


Obviously less than ideal, but possible.