If it's available at all (seems to come and go), it's in the Samsung Zone section of the marketplace. If you have a Samsung gen2 phone, but for some reason don't have that marketplace section, enable it using the Samsung OEM Marketplace XAP (see my signature).
If you aren't on a Samsung gen2 phone (Focus Flash or Omnia W; the original Focus and Omnia 7 don't work) don't bother trying; it won't work on those phones unless they changed that just recently. A non-Samsung phone won't work at all (though in theory an HTC with a custom ROM could be made to, if somebody included the Samsung drivers in a custom ROM for HTC... interesting idea, but I'm not a ROM chef).