I think it's extremely unlikely it survived. It depends how much water got into it and where it went. Not only does the headphone plug not seal the hole (there needs to be some clearance else getting it in & out would be a struggle) but at least the hold switch and the perimiter of the control pad is not at all watertight and the bottom plug is open as you say. In addition, all the ions dissolved in pool water make it an excellent electrical conductor.
Best bet: pry the halves apart (the metal back from the acrylic front), unplug everything you can, splay out what can't be unplugged, and let it dry out for a couple days. Especially unplug the battery ASAP.
Google for opening the ipod for battery replacement for more details. Without appropriate tools it's very likely you'll damage the case (a thin blade knife would probably help), but IMHO you have nothing to lose.
At the very least, an eviscerated ipod would make a nice conversation piece or perhaps a basis for an art project...
Whitebox PCs and an old Dell Other OS (Slackware & SuSE)-- GTKPod - Grip - CastPodder - DRM Free