Add me to the list: I have a Libratone Live (airplay) which works flawlessly with my windows 7 Itunes/airfoil, Ipad 1 and iphone 3GS. But with my 4S, no such luck (same issues as all of you).
FYI, I contacted the Libratone support staff and they quickly came back to me saying that:
1/ it's a known issue affecting ALL iphone 4S (not other iDevice) whatever the airplay device you are trying to stream to.
2/ Apple is aware of the problem and is working on a fix but no ETA for that.
The above means that there's no point in fiddling with your network settings or what have you for hours like I did or returning your "broken" 4S for a new one because that won't fix the airplay problem. You "just" have to be patient and hope that a fix is coming down the line.
As suggested by another person, you can remote control your PC Itunes using the 4S with no issue at all (except that the PC has to be powered on obviously), or airplay DLNA content using an app such as "Media:connect" but for the time being streaming music directly from your iphone 4S is not a working option.
Message was edited by: cdubaldo