Just wanted to confirm for all people with upgraded mac mini. If the mini originally came with a Core Duo and has since been upgraded to Core 2 Duo. It will in fact run snow leopard in 64 bit mode. The chipset is still limited to 4 GB of memory and apple has not enabled 64bit kernel in the WWDC version (see this), but all apps are 64-bit. and it is wicked fast.
woot.
woot.