Most people buy macs because of the OS, not the hardware.
I'm looking for a small, HD-capable media center to run XBMC, so the OS becomes less important. Apple has had the perfect form factor and let it languish on the back burner - I'd have bought two Minis immediately if Apple had made even moderate improvements in the last 6-9 months. Along comes Dell with something that has to be considered competitive at the very least.
Unless Apple surprises me next Tuesday (which I doubt), at least one of these little Dells will be making its way to my house in August...