Hi treehugger,
Post #2 here and the foundation thread have more information about foundations and which ones are best for different types of mattresses.
A latex mattress generally does best on a firm non flexing surface with even support from wooden slats that are no more than 3" apart (and preferably less) and have enough surface area compared to the gaps between the support surface to prevent the very elastic latex from working its way into the gaps over time
There are some people who feel that a solid surface is also fine but there is no consensus about this and a support surface that doesn’t provide ventilation can be more risky for mold and mildue as well as dust mites (see post #10 here).
There are also many people who believe that a wire grid foundation (that doesn’t flex) is also fine but this would also have some risk of the latex compressing into the gaps over time (see post #10 here).
In some cases a latex mattress (particularly one that is thinner) may be designed to be used with a more flexible foundation such as a box spring or flexible slats underneath it as part of a “sleeping system” where the more flexible base is designed as part of the overall feel and performance of the system but these would also have a larger support surface that would support the latex well.
An inch or two of very firm polyfoam (which is stiffer than latex) or something like the bed rug here can help even out larger gaps and provide a more supportive surface which would make it more suitable for a latex mattress.
Phoenix