Apple: Quad-Core Processors in New Macs [Updated]
In it, Apple claims:
Every new Mac features powerful dual-core or quad-core Intel processors, the world's most advanced operating system, and more.
At this time there are no Quad-Core Intel processors being used in any Macs, however, they may simply be referring to Quad-Core Mac Pros, which do contain two Dual-Core Intel Processors. Apple UK's store had previously had a more revealing slip up with the claims of "8-core processing power" on Mac Pros -- which they quickly corrected.
Rumors of Apple's use of Quad-core processors began in November 2006, with expectations that an 8-Core Mac Pro was coming soon.
Update: Apple has changed the text to "Every new Mac features powerful dual-core or quad-core Intel processing"