I went back to Apple in NYC (SoHo store) this afternoon and they had the black (even thought the person on the phone said they weren't in yet).
I couldn't resist and bought one. Very cool! I'm glad I bought it.
I have a white one (glossy) on the way which I ordered because I have the white iphone. The matte finish on the black is a little to get used to and there is one tiny imperfection on the top (barely noticeable- I'm just being anal). Overall, it's great. I'm very happy with this. I'll probably return the white when it arrives unless it's better then the black (I doubt it).
I gotta say, for a hard case, it hardly adds any size. Not to mention it really preserves the feeling of the curves and lines of the 3g design.
One thing to note, when I first pushed it in to the top part it created some air under my Power Anti-Glare film. I think this happened because the film wasn't on totally straight. I messed around with the film and screwed it up. I wound up using the 2nd film from the 2-pack I had making sure to put it on very straight and put the slider back on....PERFECT!
BTW, the slider won't work with any of the skins (IS, Ghost Armor, etc). I took the Ghost Armor off the back and now I have the Black Slider and Anti-Glare film on the front. Seems like a great combo. I'll post my thoughts about the white when it arrives. I'm happy to post pics if anyone wants....