"Probably not". The 320M-equipped Mid-2010 Mac Mini has a 3DMark06 of 4400.
Before the Mini I had a homemade desktop with a conroe Core2Duo, 4GB of memory and a GeForce 8800GT - which had a 3DMark06 of about 13,800. For WotLK, this was enough for 1440x900, 2x AA, 2x AF with view distance set to 2/3rds with a reliable 60fps, dropping to about 40fps in 25-mans, and about 25-30fps in Dalaran, with a decent number of mods that were not memory intensive (< 32MB total footprint) or CPU intensive. I could crank it up to 1920x1200 without AA/AF, but Dalaran framerates tended to plummet to around 15fps.
To optimize for things like Dalaran, your framerate limiter is actually your disk. The reason being you have to load new textures/models into the cache before they can be displayed in the game viewport. I was aware that simply replacing the 7200rpm hard disk with an Intel X-25M at a time would've pushed Dalaran framerates to 60fps.
However you still need decent fill-rate, which is hobbled by shared memory, and the 320M isn't a shader beast as well.
The best comparable system that Apple makes would be the new top-tier 27" iMac, which should run 1680x1050 to 1920x1200 with 2xAA/4xAF without any issues on high detail.