[R-sig-Geo] Which points fall in which polygons?

[Alexander Shenkin]

Hello folks,

I have two data sources: an ESRI shapefile (UTM/WGS84 projection) of
numerous polygons, each of which have one of two values (burned [=1] and
unburned [=2]); and a set of X/Y distances from the corner of the
polygon that represent tree locations.  I'd like to tag each X/Y point
in the set with the value of the polygon within which it falls (i.e.
whether that tree burned or not).

I've read the polygons in with rgdal, but I'm not sure where to go from
there.  I'm not sure which functions from which packages apply to rgdal
objects, etc.  I've looked at the rgdal manual, but I don't understand
how to manipulate the objects once i have them in R (e.g. how to perform
intersections and the like).  Any help would be greatly appreciated!

Thanks,
Alex