tada! the answer is:
SSH

ok maybe it's a little complicated. easy to chew answer:
SSH application for the iPhone it's a protocol used to access the iPhone and transfer the files over the wireless network.

so, when u don't need it, just turn it off. it saves battery power.

errr...search button, where are you?

haha...btw it's always the best practice to turn off SSH when not in use, otherwise other people can freely FTP / SSH to your phone (provided u keep intact the same root password). not only it will drain your battery, hehehe...

mmm...maybe u also interested to experiment with SSH, so u need software such as WinSCP to perform SSH. then your iPhone can be a wireless storage drive (if u need to). btw most people SCPed into the iPhone for transfer and install applications into it.

or maybe u can just uninstall SSH if u don't see the need of using it in future.