Not a bot -- a phone somethingorother:
71.sub-174-252-2nn.myvzw.com
Mozilla/5.0 (iPhone; CPU iPhone OS 5_0 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Mobile/9A334 iPhone3,3 BingWeb/3.0.952.20111012
Scant info on what it does, just that it gets around -- but not much. Only 187 G results for "BingWeb/3.0". Presumably, it's MSN Bing-related.