Greenspun owned Vegas.com has launched a mobile site for cell phones and smart phones featuring show and event info, as well as some hotel and restaurant data. They also have a text messaging interface for some cell data.
It seems like a reasonable first effort, though the mobile site does require a ton of link clicking/tapping to get to the goods. I expect it to improve and maybe someday be the primary driver of their business.
Anyone that's followed this site for any period of time knows that I'm pretty bullish on mobile for stuff like this. I've had a cell phone/BlackBerry site for 2 years, an iPhone optimized site for one year and in maybe a month or so, a native iPhone app that integrates with the GPS for even more 'wow' factor (I was just going over icons with the designer today).