Show it a month before 360 is out, so it'll be plastered on the front page of magazines at the same the 360 is out (Sony will still have 4-5 months to copy the controller, however). Anyways, along with the Zelda blowouts that will no doubt make it to the front page (and release the same time as 360), and the DS going online, the 360 would have to share the limelight if they timed these announcements correctly.
Buy out some simple ads, showing a Mario glove and Link triforced hand about to punch each other, with the words "SMAAAASH" plastered across the page, alongside "online, for revolution members only". Get more specific ads as the release date is closer. They definitely should release some demo reels in the next several months so the specs aren't ragged on and given bad press. Or even offer bonuses for those who preorder the Rev and not the 360, if they could somehow make that work. Should provide for some good momentum