People who have gotten OS X working on Atom-powered netbooks say it's really slow.
Not true.
But I am a bit bemused as to why Atom would go into a desktop, other than a media centre sort of machine. I was actually thinking of an EEE Box to go under the tv, but I might hang off to see what pans out on this.
Out of interest this is where the Atom 330 stands in processor benchmarks (From here)