hmmm, i've never known GAE to cache selects. at one point i thought the book said as much, now it simply says:
"The results of a select are complex, un-pickleable objects; they cannot be stored in a session and cannot be cached in any other way than the one explained here." and i believe that un-pickleable means not memcacheable. reading dal.py, select() in the GAEAdaptor does not seem to do anything with cache. (maybe i'm mis-reading it)