Expensive 2 GB modules required for maximum RAM, cannot be matched Core 2 Duo (Late-2006) MacBook Pros can be expanded to 3 GB of memory, unlike their predecessors (Early-2006, Core Duo MacBook Pros) which could only be -- officially -- expanded to 2 GB of RAM.
Unfortunately, achieving the maximum RAM configuration requires installation of an inordinately expensive 2 GB RAM module. OWC, for instance, offers the new 2 GB module (manufactured by Samsung) for US$680.
Also, note that by installing the maximum 3 GB of RAM, it is impossible to match RAM pairs. In order to install the maximum RAM, one 2 GB module and one 1 GB module must be installed. Installing two 2 GB modules would net 4 GB of installed RAM, but the system would only recognize 3 GB. Not only would the purchaser be wasting several hundred dollars on the bigger module, but it is unclear if matched-pair speed benefits would be apparent.
Strangely, the board likely used in the new MacBook Pros, the Intel 945PM, supports 4 GB of RAM according to specifications. As such, it is undetermined why the Late-2006 MacBook Pros can address only 3 GB.