I would personnally say that Adobe is still one of the most important contributor to photography these days, but it is true that they do have a lot more competition now than 5 or 10 years ago. You should also consider that most of the underlying software foundations (OS, DBs,...) are also designed and owned by US companies.
Some of Apple's software is not written in the States, such as Logic Pro, which is written in Germany. Apple still owns it of course. I don't know if Microsoft uses branches in other countries to write software as well. I wouldn't be surprised if they did, but then again, the only significant software Microsoft makes is Windows and Office, and that is all written in the States, I believe.
Tiny companies like DxO, Kolor,... have managed to grow niches into mainstream domains generating significant revenue.
DxO is French and Kolor is Canadian. PhotoMatix is made in Germany. The States used to have dominance in software, but that gets weaker every year, unsurprisingly, given how important it is becoming, in every country.
Another important contribution from the US is in carrying devices (bags) with companies like Tamrac for instance.
And Lowepro. However, many are not American, such as Billingham, Artisan & Artist, and so on.
I am not really sure what the point of this thread was. To lament the passing of American dominance?
The States used to be dominant in many areas of manufacturing, but as wages rose, production moved elsewhere. It is sad that almost the entire American photography industry got wiped out. I am not sure why that is. Perhaps the traditional American insistence on price as the primary motivating factor in making purchase decisions? It seems that all that is left is a bunch of niche players. Japan was probably the instigator in this move towards cheaper manufacturing, but now China is outdoing them in exactly the same fashion. I wonder how much consumer-oriented manufacturing will be going on in Japan in 10-20 years?
IMO there is too much emphasis on price, and too little emphasis on nurturing the local industries. It hurts us all when the local guy shuts his doors because they can manufacture cheaper on the other side of the planet.