I don't really know what to think about it, but I think it has to be significant that Sayid says he did not realize that it was Christmas already. From the discussion between Miles and Jack, time runs more quickly on the Island but Sayid's comment makes it seem the other way around. Regardless, it was 2004 in the real world and on the Island, so the difference in time between the two places cannot be THAT significant.
Prior to last night, I thought the fact that Jack asked the captain if the Red Sox really won the Series was significant. I expected the captain to at some point say, yeah, but that was 13 years ago. So that theory is now gone with the phone call to Penny, and I have a clue as to the final answer of the time travel mystery.