You are referring to a SSH application, not Bash - bash is the shell software running on the remote server. SSH is used to make remote connections to servers and get a commandline where you can get work done. I, for instance, live in SSH sessions every day all day - it's my bread & butter.
There are two - MidpSSH (open source, free, works but isn't the best) and Rove MobileSSH (commercial, works great, a bit expensive).
Rove MobileSSH: http://www.rovemobile.com/products/ssh/