Does the heatshield dealie in a Lombard even contact the cache chips? I don't recall if it did or not. Certainly it's super thin and rather flimsy, plus Apple decided that they didn't want to have the itty bitty fan turn on until a meltdown is imminent.

If the factory heat shield doesn't contact the cache chips, perhaps one could go to a computer hobbyist place and purchase some RAM heatsinks with the self-adhesive backings, cut them to size, and apply them to the cache. Of course, the height of the new heat sinks would probably have to be taken into consideration, but I'd imagine that once properly installed, heat problems would be less frequent or severe.