There's not a shortage of hops like Cascade, CTZ, etc. But Simcoe, Amarillo, Citra and now even Centennial are in very short supply. I can't even get a contract for Crystal and may not get any this year, and last year that was an easy hop to come by. I waited too long to look for a contract and was lucky to find one (thanks to Denny's contact). It's not going to be like the great hop shortage of '08 and '09 but it will be worse this year than it was last, especially for craft brewers.
I should add, homebrewers should be fine so I don't want to cause hysteria. It's funny you guys can still get Citra. I can't get it anywhere.