Yes there is a very nicely detailed explanation of shifts earlier in this thread.  To simplify it for you a shift is a less granular look at your contributed hash rate than tracking every submitted share.  Makes it easier on the pool to track shifts instead of shares.

Renting for profit is tough to pull off.  Phil got lucky.  He got hashing power at a very nice rate and the pool found more blocks than expected.  You can also get burned playing this game.  For example, a few months ago I rented a large amount of hash.  Unfortunately the pool on which I was mining suffered some horrific luck and I lost a lot of coin.