During a discussion of API usage with the Netflix team, they mentioned that they are seeing a lot of iQueue requests being rejected due to the device (iphone or ipod touch) not providing a reasonably accurate time stamp (i.e. current time). Netflix uses this to authenticate the request and could potentially cause some unanticipated behavior if they return an error. I assume iPhone users have their clocks set accurately. Not so sure about iPod touch users… and definitely not for pesky jailbreakers.
Long story short… check your clocks.