Terminal has gone weird after screen sharing
The default prompt in Mac OS X is derived from System Preferences -> Sharing -> Computer Name. If that is set correctly and you still see kellys-iphone in new terminal prompts, your terminal environment variable PS1 has been set in either .bashrc, .bash_profile or some other local file.

You can check which files set PS1 like so: grep PS1 ~/.*

Side note: If you see a line like this:  

[ -z "$PS1" ] &amp;&amp; return  


which just means "if this is not an interactive shell, disregard the rest of this file" - so that's not the droids you're looking for.

That should reveal a file that has a line akin to this:

export PS1="\u@\h\w$ "


Or, if I'm right:

export PS1="kellys-iphone-2:\w "


Edit that file/line to reflect what you really want. More info about custom prompts in OS X