Google: Free IMAP for everyone
You'll need to use the English interface in order to see your IMAP settings. But Google plans to add the option to all languages in the next few weeks.
Why does IMAP matter again? Because unlike POP, IMAP supports back and forth communication between your offline email client and Gmail. If you set up your iPhone, Outlook, or Thunderbird client to read your Gmail using IMAP, every time you read a message it will be marked as read on the web interface. If you delete a message on your desktop, it will be deleted from the web. If you use POP, you'll have to repeat all of those actions twice.