Don't Sort. Search!
We've received a number of questions about how to sort email by various criteria in GMail. For instance, many regularly sorted by person under Thunderbird. Sorting like Thunderbird is not possible in GMail, but GMail search is a very powerful tool and can give you very similar functionality.
If you begin to type and individual's name into the search box GMail will lookup up people from your address book and email. Once you search, GMail will return all messages where that individual was included in the message either 'to' or 'from'.
If you only want messages from a particular individual, you can click on the 'Show search options' link next to the search box. This will allow you to search specifically 'from' or 'to' someone along will many other search options.