sync Icon On my Top Menu Bar Suddenly Appearing !

Hi,

After 3 weeks of Lion, Icloud and Ios 5 Update, I notice the sync Icon on my Top Menu Bar. On clicking it it shows me SYNC NOW option.

What is this for ? It was never there earlier and I have not changed a single setting & not done any recent updates either. Why is this suddenly appearing. On Googling for the same it shows only how to remove it by Option Dragging it off... But does not say how to get it back. Do i need this ?

The only change I Notice just yesterday when I saw this Sync Symbol, is that on adding or deleting Calendar events on my Iphone, I would have to launch iCal on my Imac Earlier to see the updates. But now even though iCal is off (QUIT), it automatically launches and updates the entry. This is great but I only want to know how is this all happening automatically since just yesterday.

On my other User profiles it is not hapening automatically and the sync icon is not visible !

Please help.

thanks

cyrus !