If you use POP or IMAP with an stand alone mail client (Mac Mail, Thunderbird, etc.), you will be able to continue to use POP or IMAP, but you will have to change some settings. Configuration information:
Links:
[1] http://www.humboldt.edu/its/google-macmail
[2] http://www.humboldt.edu/its/google-imap
[3] http://www.humboldt.edu/its/google-pop