From the Cydia FAQ:
"Q: I installed OpenSSH, but I can't figure out how to turn it off. It's eating all my battery power, and the iPhone already lasts only five minutes, so now it turns off before it even starts.
A: OpenSSH does not use any battery power except when you are actively talking to it. It isn't even running. It is just a data structure in the mind of launchd, which is always running, OpenSSH or not. There are no good reasons to deactivate OpenSSH on your phone."
So apparently the rumor about it eating battery is false. Also he mentions in the FAQ you can change the default password with the passwd utility. Something that was broken in Installer's BSD Subsystem.
If you goto the main page of Cydia on the iphone and Frequently Asked Questions, he has some good ones in there.