It's true, corn is now legal in WY and as far as I know UT is the last state where it is illegal. This reg change was relatively simple for WGFD, they basically just deleted it from their regulation book without promoting it publicly. I've had hopes of removing this regulation the past couple of years in UT. As someone stated, there's long been an urban legend that corn is lethal to trout, but as we know it's technically not lethal. Truth of the matter is, corn passes through fish almost undigested (like us!), offers little nutrition, and could decrease trout condition and growth if that's the only food available. As most have noted, corn is a viable and productive bait for trout, warmwater panfish, and yes- kokanee salmon. It's always DWR's and WGFD's goal to try and maintain regulation consistency across the stateline (on the Gorge) as much as possible. It makes it so much easier on anglers. There are some variations like Downrigger noted, based on state statutes or even biological differences such as the "10 bass creel limit" on the UT side and "6 bass creel limit" on the WY side. DWR staff recently submitted a proposal for a regulation change on the Gorge, to legalize corn as bait, but if approved it wouldn't be effective until 2015. So far it seems to have more support, especially from DWR law enforcement who would rather avoid these inconsistencies on the water.
Until then, I would suggest being careful not have corn in your possession in UT, even on the Gorge, until the regulation is addressed. Sorry for the confusion, Ryan