How to periodically run a task within emacs?

How to periodically run a task within emacs?

As i'm rather fan of FS, i just had a look in Emacs a gain, TKS many awised one in Identi.ca..., and another link there :

http://blog.nethazard.net/identica-mode-for-emacs/

Among many others pages as :

http://www.andrews-corner.org/mutt.html#download