[Other]

Maybe I am just being daft but what was the reason for the signal being blocked from there, Ben did it but the rest of the others didn't know and thought they were stuck on the island.

What happened to The Looking Glass when the Island moved?

[EvilGrouse]

Didn't the small island disappear when the big one did? If so, then maybe the island's moving device creates a bubble around it, and anything in the vacinity just goes along for the ride. So it's there now. That's what I'm thinkin.

[J_C]

Originally Posted by Other

Maybe I am just being daft but what was the reason for the signal being blocked from there, Ben did it but the rest of the others didn't know and thought they were stuck on the island.

What happened to The Looking Glass when the Island moved?

Any answer to this question, aside from any spoiler info, would be speculation.
So here goes

When Desmond turned the failsafe key an electro-magnetic pulse issued from the area. The electro-magnetic force was so strong that it was perhaps even visible, bordering on the ultra-violet (very high) wave frequency ("the sky turned purple"). This was detected by the two guys employed by Penny at the cold climate monitoring station.
Now the speculation.

Theory #1
When this occurred Benjamin Linus realized the significance of what happened. If there was anyone looking for the Island, and he knows Widmore is, then the general location of the Island could be gleaned from the detection of the pulse. So as a preventative measure, he sets up communication jamming as an obstacle for those who may come looking.

Theory #2
Ben took advantage of the communications break caused by the electro-magnetic pulse and had communications jammed under the guise of "the sky turned purple" phenomena to further isolate his people in an effort to garner greater control over them.

Could be both.

The Looking Glass is presumably still with the Island. A diagram of the station was shown indicating an 'anchor' to the Island.
This 'anchor' is the cable that both Sayid and Hurley followed leading (indirectly) to Danielle Rousseau.

If that be true, then it brings up a bigger issue. It seems to indicate that the DHARMA Initiative was aware of the Island's ability to move.

[LightSide/DarkSide]

The bubble theory makes sense. The Hydra Island moved as did Daniel's boat. He hadn't yet made it back to shore before the first skip. Also, Jin was still out at sea drifting on a piece of debris from the freighter. He skipped with the island as well.

Originally Posted by J_C

If that be true, then it brings up a bigger issue. It seems to indicate that the DHARMA Initiative was aware of the Island's ability to move.

We know from Hawking's lesson at the Lamppost that they did know the island was moving. "They stopped looking for where it is and started looking for where it would be." Or something like that.

[concusion]

The Looking Glass was used to block incoming and outgoing transmission signals, once Charlie turned it off they were able to call the freighter.

[Killfetzer]

Originally Posted by EvilGrouse

Didn't the small island disappear when the big one did? If so, then maybe the island's moving device creates a bubble around it, and anything in the vacinity just goes along for the ride. So it's there now. That's what I'm thinkin.

Daniel explicitly said that his boat was "inside the radius". This strongly indicates a bubble like effect.

Originally Posted by J_C

The Looking Glass is presumably still with the Island. A diagram of the station was shown indicating an 'anchor' to the Island.
This 'anchor' is the cable that both Sayid and Hurley followed leading (indirectly) to Danielle Rousseau.

If that be true, then it brings up a bigger issue. It seems to indicate that the DHARMA Initiative was aware of the Island's ability to move.

It would be relatively dumb to create a station to jam all radio transmissions and don't have a possibility to contact it without radio...
The cable was simply a power/communications cable.