According to Apple, you can install up to 4GB RAM on the Macbook 7,1. I installed 8GB (2x4GB) in mine, and it works flawlessly (it seems like Ubuntu runs faster than Lion now). But today I discovered this with dmidecode:

Handle 0x0006, DMI type 16, 15 bytes
Physical Memory Array
    Location: System Board Or Motherboard
    Use: System Memory
    Error Correction Type: None
    Maximum Capacity: 32 GB
    Error Information Handle: Not Provided
    Number Of Devices: 2
Can this really be true?