I like how the show keeps all the viewers guessing. That element of "Whoa" always lingers at the back of my mind that something supernatural is going to happen, yet the show generally keeps it real as they are still castaways stuck on an island and struggling to survive.
To be honest I was a bit disappointed that it was only another crazy british dude in the hatch, but that tune he seems to like is really catchy and Locke was once again acting strange, which means he knows something else is going on on the island.
Theories:
-The new character Desmond is a time traveller?? He referred to himself being a world traveller to Jack and then he told him, "What would you do if she were alright?" Maybe he knew because he'd already seen it happen.
-Desmond in control of the island? He controls the monster, or the whole island itself.
-Michael, Jin, and Sawyer not coming back? Considering they were miles offshore and the raft was blown to bits.