GET can still be used to retrieve information from a form, it's just that that information is passed from the form to the server via the address / URL.

Traditionally, GET was used as a way of getting information whereas POST was used to send information. That is to say, traditionally a GET request should not make changes on the server (whereas POSTs can).

This is actually a good way to think, anyway. People that have browser accelerators that prefetch URLs will have lots of problems if GET type URLs are prefetched and if those URLs actually make a change on the server. Imagine prefetching 100s of URLs that are actually 'Delete this Entry' type URLs!