AppleTV 3 wakes iMac every 10 minutes Until recently, I left my iMac (27" late 2009) on all the time. I now want to sleep it when not in use, but also wake it remotely via my AirPort Extreme. All this is working fine. The iMac is set to sleep after 6 minutes.

I have an AppleTV 3 and when powered on (but sleeping) it causes the iMac to wake every ten minutes. greping for wake in system.log shows a bonjour service connection approximately every 10 minutes. After lots of mDNS debugging I narrowed it down to the AppleTV (there are iPads and phones and other Macs around, it wasn't my first thought). Unplugging the AppleTV proved this - the iMac has been asleep for 8 hours now.

I do have home sharing enabled. This is pretty much all it's used for.

Has anyone come across this before and know what's going on?
After Apple TV Software Update 5.1, I comfirmed this issue was resolved.
Try to update your FW!

The following my old comment is for old FW. I leave it just for knowledge.

I had have same problems. I know Snow Leopard's mDNSresponder wakes a Mac every 2 hours during sleep. So a similar thing occurs on AppleTV every 10 minutes, I guess. 

In my case, AppleTV woke my Mac If I set Home Sharing on it. So, 1st option is disabling HomeSharing.

However, I didn't want to do that. So now I avoided this to kill iTunes before Mac sleep. This means it doesn't register Home Sharing service for sleep proxy.

Note: 
 1. You have to wake up your Mac by some method(http, ssh, magic packet or something) when you want to use your Home Sharing.
 2. You cannot use sleepWatcher to make 2nd option because it's too late for killing iTunes after sleep trigger. So you must check IDLE time and sleep timer.