I just installed MidpSSH on my SonyEricsson K750i. It is an SSH and telnet client for MIDP (1.0 and 2.0) devices. It works as expected! I can ssh to my servers from my mobile phone and do whatever I want. (Of course K750i's keyboard is not very useful for typing long shell commands, and the screen is quite small, but... it's so much better than nothing!)
It is reported to work with blackberry devices too -doing something more complicated should be much easier on a device with a "real" keyboard.