You didn't miss anything. U3 is currently Windows-specific, and it doesn't provide anything that couldn't have been done using well-documented Windows programming guidelines beginning with the release of Windows 95 and its support for autorun.inf on all removeable media. U3 does, however, save developers time (i.e. they can once again ignore Microsoft's guidelines and the benefits of a common operating environment). Ever wonder why Macs and Amigas are so easy to use? For some strange reason, developers on those platforms actually design user interfaces that are consistent with the operating system.
Trev