You can load any carrier's upgrade release, just follow the directions.
Here is yours: http://www.blackberryforums.com/gene...ilanguage.html
US Cellular is not being overlooked... it is their own choice to release it or not, RIM does dictate who gets to or not. AT&T, one of the largest carriers, has not released 4.5 yet either, while Cellular South, one of the smaller carriers has.
You will be fine to do the upgrade.