I have a feeling the glue is to just help with flex, but I really don't know exactly why the corners are glued.
Just like the Microsoft did with XBox 360 to stop the Red Ring of Death. Shame since it was one of the few Macs that could be tinkered with.
I bought it with the intention of upgrading.....I was going to try a number of 1066Mhz FSB Mobile C2Ds....