Just like the iMac line, the Mac Mini line has also been upgraded today, albeit with just a speed bump. Instead of getting Core 2 Duos like their screened big brothers, the Mac Mini now has a 1.83GHz Core Duo in the $799 model and a 1.66GHz Core Duo in the $599 model.
Both of these have a 2MB L2 cache, 667MHz frontside bus, 512MB of DDR2 memory standard, and built-in AirPort and Bluetooth 2.0. The 1.83GHz model has a SuperDrive (DVD writer) instead of a Combo Drive (CD writer, DVD reader). Still standard shipping in 1-2 business days.
Product Page [Apple]