I just opened up my Early 2009 Mini and took the heatsink off to find.....the processor is glued down like in the XBOX 360s. Dangit!!! Thought I might be able to go up to the T9600. Oh well.....
The glue doesn't hold the CPU down though. The CPU would stay just fine with the ball grid array being soldered directly to the board. I have a feeling the glue is to just help with flex, but I really don't know exactly why the corners are glued.
Yeah but I don't fully understand why, as the glue will flex too... and the heat sink has enough downward pressure to hold it in place, you would think.
The cpu is becoming a minor component with the advent of Snow Leopard's OpenGL. If Apple's to be believed, your 2-core Mini will become an 18-core system after you put SL on it. We'll see...