It's actually the "*" key on the numpad now.
In addition to being the "-" key? Or as a replacement. Haven't tried to screenshot lately, but last time I did, it was the "-" key. I'd also be shocked if someone had a "*" on their keypad, but not a "-" (since they're all arithmetic keys, so you should have them all, or none of them).
Oh, for some actual valuable information, don't forget about the F11 key (I think it's F11, might be F10). It toggles you in and out of "no UI" mode. Basically, it'll remove all UI objects on your screen. No chat bars, menus, spell gems, hotkeys, etc. So if you want a picture without any of that stuff, it's pretty darn useful. It's also useful to know in case you ever accidentally hit it, cause you can't get out if you don't (no UI, remember). Fun times!