I found the sand snare in the Sandstorm adventures setting booklet and it has some very interesting language. This is a feat that kicks in after you have tripped someone in loose earth or sand-like terrain. It specifically says a creature must spend a full-round action to get themselves out of the terrain and then they can stand up from prone as normal. Would this then mean characters with kip up(and like abilities) would still need to take the full-round action?