I liked it better when being Blind meant that everyone was considered invisable. I think this is just a case of forgetting to add the ability to retain dex bonus while blind to both uncanny dodge and blind fight. In fact, the wording of uncanny dodge, " At 2nd level, a barbarian retains his Dexterity bonus to AC (if any) even if he is caught flat-footed or struck by an invisible attacker. However, he still loses his Dexterity bonus to AC if immobilized." seems to imply that only 3 conditions make you lose your dex bonus. Errata, anyone?
In the PHB, the flavor text for Uncanny Dodge seems to imply that it would definatly work in darkness, namely, ".. a barbarian gains the abilitie to react to danger before his senses would normally allow him to do so." In darkness, his senses would normally allow him to react to danger only after he had been attacked =)
I'm putting my vote on errata, seeing as how I think this was an unintended change.
Eldorian Antar