iPhone - Status Bar

Hi,

I have noticed a new item on my iPhone status bar that I haven't really noticed previously.
Next (at the left side) the bluetooth icon I have a circeled lock.

I can find anything about it in the user guide and was hoping someone here (even though it's probably so painfully obvious) could shed some light. It's killing me not knowing.
Thx,
Marc

That's the orientation icon.

From another forum:

That is the orientation lock for the screen. Double tap the home button, this opens the multi task screen. Now slide from left to right, you will see ipod controls and a symbol to the left of the controls. That locks and unlocks the screen.

Click to expand...

Regards