I started to do some work on how efficient the spacial SQL queries I was using are. That meant looking at the indexing that is used on the geometry column and understanding the functions I used a bit more.
I made a simple change from using ST_Contains to ST_Within and made a tenfold increase in the performance of my query. Similarly with a change from ST_Distance to ST_DWithin.
Now if only I read the documentation more!
Prior to 1.3, ST_Expand was commonly used in conjunction with && and ST_Distance to achieve the same effect and in pre-1.3.4 this function was basically short-hand for that construct. From 1.3.4, ST_DWithin uses a more short-circuit distance function which should make it more efficient than prior versions for larger buffer regions.