I received my Mini 9 from Dell on Tuesday and, with the help of some great posts in the forums, now have a happy, tiny OSX machine. It's handled everything I've thrown at it beautifully with the exception of video out. This is a problem as I bought it specifically to run Keynote presentations on external displays.
I use a pair of plasma TVs through a VGA splitter. When I connect the Mini 9 to the VGA cable the external monitors and internal LCD corrupt (multicolored vertical lines) though I can still see a mouse cursor. Judging by the cursor, all displays are at 640x480. All displays support 640x480, though ideally I want to run the internal at 1024x600 and the externals at 1024x768 (again, all supported resolutions for the hardware).
I do not have this problem if I connect the Mini 9 to other displays. It seems to work swimmingly with my Dell LCD monitor.