Update: 28th September Thanks to Marisa for the heads up on this which seems to confirm things that were recently posted in the Rumours section.
I believe that's Rob McElhenney from It's Always Sunny in Philadelphia - he played Aldo on Lost.
Source: LeahVautrot@Twitter
Thanks to Erik for the following.
Preston and Steve Morning Show WMMR Philadelphia
The Preston and Steve morning show on 93.3 WMMR are friends with the cast of It's Always Sunny In Philadelphia, starring Rob McElhenney. The cast of IASIP was in Philadelphia last night to perform their musical "The Night Man Cometh." This morning, Preston revealed that, while speaking with Rob McElhenney, who played Aldo in "Not In Portland," was given the script for Lost to make at least one appearance in the final season. This comes almost straight from the horses mouth. The only way to verify would be to get a quote from Rob himself.
Source: Erik via Preston and Steve Morning Show
