How to add Presence to your custom web parts

How to add Presence Information to your Custom Web parts
To add presence information to your custom webparts, you simply need to call thefollowing javascript function IMNRC() function, passing in the email address of the account you wish to check, such as IMNRC('info@sharepointstudio.com')

This in turn calls a ActiveX control, name.dll, on the users computer.

User Presence:
User