minicom is already on most distros..
search for Cisco minicom to find linnks to how-to's for that particular task.
putty is available as source code for Linux.. you just have to compile it yourself.
http://the.earth.li/~sgtatham/putty/...ty-0.60.tar.gz
[EDIT]
I just downloaded and compiled putty
It does have the GUI front end, and it does have the serial option.
looks like a win \@/