I was having this problem, Googled, and was led to this thread.
Got a new Apple TV this week, got it going, started streaming Netflix, and lo and behold it stops very frequently. Sometimes it's a stop for 30 seconds to a minute and it picks back up after, but more often it just stops for very, very long periods of time (been frozen for 15 minutes now 14 minutes into a "30 Rock" episode - it's not just waiting to buffer, there's something else wrong). Am using it wirelessly, Time Warner "Webstar" box to D-Link wireless router.
Checked my speed, get consistent 14 Mbps/40ms wired and 10 Mbps/50ms wireless. Like everyone else, I have a lot of other wireless devices (iPhone, laptops, etc.) that stream fine. I have them all turned off so they're not using my WiFi right now and the ATV is only like 5' from the base station. I read this thread last night, so tried unplugging the ATV overnight, plugging in power, then HDTV, then trying again. No effect. In a given half hour show it will stop for these 5+ minute spans multiple times, making it totally unusable for streaming, I guess it's back to the 360. I'll try wired once I obtain a spare cable. Lame. And this isn't "throttling," that wouldn't stop you for 15 minutes at a time. Making sure to tell my friends "don't be tempted to get one of these for Netflix streaming..."