From Mac Guides
Apple introduced the Mac mini in January of 2005 as the smallest and least expensive desktop Macintosh ever. This line of Macintosh computers was originally built on the PowerPC G4 processor family, but was later transitioned to using Intel Core chips. In 2010, Apple redeigned the Mac Mini to an Aluiminium Unibody Enclosure.
On 15th June 2010, the newly redesigned iMacs quietly appeared on the Apple Store. The biggest change with these new Mac Minis was the inclusion of HDMI, a first for an Apple computer. The new Mac Mini had slight specs bumps and an increase of $100 on the base model.