LazyWeb I beseech you.
I could use a pure geographic bounding box library or server that does for geoqueries what Sphinx does for full text search. Maybe a bit prickly, idiosyncratically extensible, horizontally scalable, and fast as hell by default. Throw in uniquely identified polygons, take queries for all intersections or all contains, return ids. That is all. No transformations or manipulations, just insert, delete, index and answer queries.
PostGIS is great, but the performance of the geographic indexing seems opaque and hard to optimize, at least to this simple soul.