The Gmail team has launched what should have been a standard Gmail feature since its inception. An option to import your mail and contacts from accounts like Yahoo!, Hotmail, AOL, and other buttload of webmail services.
There is also an option to keep fetching this data for 30 days. So that you can test drive Gmail and make up your mind.
This should make it easy to convince friends and family members to switch to Gmail, especially those who, for some unknown reason, are madly in love with Yahoo! mail.
[via Official Gmail Blog]