The easiest way, to do a point in polygon, is mathematically; you don't actually need to invoke any GIS (which always has an overhead), all you need to do, is use something like Java script to calculate if a given point is within a given set of co-ordinates, which make up a polygon. I think I may even have soem java code somewhere we can be, very, easily rtranslated into Javascript, which needs you to pass ina string of polygon coords and the point coords. Always, always, try and keep things away from a GIS if they can be computed mathematically, as all you are going to do, is invoke a middle man, to do the same things, which cost time and money and, after all, a computer is best at crunching numbers.
That's my opinion anyway. I'll mooch through my libs later to see if I can find it, but, essentially, it is quite a simple mathematical issue
EDIT
I found this very easily:
Point in Polygon
And also this:
Google Point in Polygon
Either way, much better do this the first way using Math