what?? which pieces are blurry? mine look great!
iPhone app blurry on Retina display
They all do; I tried switching to different sets of pieces. It looks like you upscaled the images from the low-res version, or maybe they're saved as jpegs... I don't know, but the edges of the pieces just look fuzzy. Download Stockfish (free) and switch between them.
Here is a comparison picture I made:
http://dl.dropbox.com/u/28708249/stockfish%20vs%20chessdotcom.png
The pics weren't compressed at any point. PNG screenshots from my phone -> cropping on the computer -> PNG screenshot of the two together. I think this proves pretty clearly that I'm not imagining anything. 
I just wanted to let you guys know that the pieces are blurry on the iPhone 4. If you open an app like Stockfish and use the same piece set (I like Alpha), you should easily see the difference and how crisp the pieces look in that app. I figured this would be an easy thing to fix in an upcoming release. (I couldn't find the proper forum for this--sorry if it's in the wrong place.)