Don,
When I first read your proposal casually, I had a hard time understanding it, namely separating your information about the existing implementation (util_memoize), what you implemented previously, and your proposal.
The recommended format for TIPs is described in TIP #2. Basically the different parts of the proposal are labelled with standard headers. This would make it easier to read and understand TIPs quickly. Imho TIP #29 is a good example of the suggested format.
I'd suggest that future TIPers keep this in mind.
Thanks, Guan
