What it means is that US customers can codeshare on UA international and domestic flights, but not on flights operated by UA's STAR partners.
As for codesharing being a smoke and mirrors game, I completely agree. But even though I dislike it, I recognize the need for it today because it generates a substantial amount of revenue for the carriers involved. US codesharing on UA flights and vice versa will generate additional revenue for both airlines. There is no sharing of that revenue. US pockets all the revenue from the passengers they carry on their flights, and UA pockets the revenue from the passengers they carry on their flights. So it's a mutually advantagious relationship. Does it confuse the consumer? Yes, it does. But it also offers the consumer access to an extensive network of city pair options that can be seemlessly ticketed, as well as offering customers the ability to earn miles and enjoy the perks of each carrier's offerings. I don't view this as UA taking advantage of US. Both carriers are struggling. The incremental revenue that will be gained is needed by both airlines.
KCflyer,
The same example you gave would work in the reverse in a market like, say, PIT-DFW, where US is the nonstop carrier and UA has the one-stops. Does a UA res agent sell the nonstop and give the revenue to US, or sell the one-stop and give the revenue to UA. It's going to depend on price and schedule convenience most of the time anyway. More often than not, you'll end up selling the nonstop irregardless of UA or US being the operating carrier. That is how codeshares succeed. Each carrier contributes to a bump in load factor that translates into additional revenue for both carriers. Or at least, that is the idea.