Update: 13:45 GMT Thanks to Al and others who sent me this extra info.
On Radio 1 on Jo Whiley on Monday. Naveen Andrews was been interviewed and he said something similar to what has just been posted in the spoiler section about been in another dimension.
Can you link the interview to the site as its quite interesting. I hope for his sake he hasn't let the cat out the bag.
http://www.bbc.co.uk/radio1/listen/
Source: BBC Radio 1
Here is a little snippet from a recent Sky One interview with Naveen Andrews.
Iain Lee: "[In series 3], there were some of the best episodes. Desmond, and the "Flashes Before Your Eyes." Jumping through time. Whoa, that was good.
Naveen: "Well, there will be more of that, I think. Different dimensions."
Iain: "Different Dimensions?!"
Naveen: "Rocketed into the Fourth Dimension!"
Source: Sky One