I use a gmail account but I don’t see how to easily group or find email from a certain person.
And I know there are other features others must want.
But what’s Outlook? :)
(I use Apple Mail and Entourage too.)
You can create a filter which applies a label to that person's email. Labels are GMail's equivalent to folders, but they are more powerful because you can cross reference them.
Additionally, you can type in that person's name or email address in the search box and pull them all up.