It means very little in the prices we pay in the long run (2yr +) and short term (3mth) but may pay slightly higher in the middle there but not by much (couple of %). Exchanges keep everything in line for the most part for consumers. Companies may get hit and we may see a slowdown in new releases but that would be a company by company impact. Nikon and many other companies re-evaluated many projections and prices recently that move everything a bit higher (as we have all noticed).
"national debt crisis and a massive devaluation of the yen" - all political babble written by an English major reporting on finance. The downgrade was very small in reality - basically the difference is the same if you or I paying 5% interest Vs 4.8% on a 30yr mortgage is all the change is.
Not a good thing, but certainly not any sort of a panic either.