As most of you know, MobileTerminal doesn't work correctly with iOS 4; however you can access Bash on the phone via SSH (provided you've remembered to install openSSH via Cydia). Then I remembered a trick that was mentioned a while ago; opened iSSH and told it to connect to the loopback address (127.0.0.1). Logged in as root with the default password of alpine and sure enough I had access to Bash locally on the system. Used the passwd command to change the password (you'll want to be sure to do so for both root and mobile) and am golden. iSSH is available on the app store for $10, and the cheapest SSH client on the app store that I could find was $2, but it'll get you there until MobileTerminal is updated.