The next version of the Fortran standard after Fortran 2003 is currently being worked on by the Working Group 5 of Sub-Committee 22 of the Joint Technical Committee 1 of the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). This group is known as WG5. The next revision of the Fortran standard is informally referred to as Fortran 2008, reflecting its planned release year. The GNU Fortran compiler has support for some of the new features in Fortran 2008. This support is based on the latest draft, available from http://www.nag.co.uk/sc22wg5/. However, as the final standard may differ from the drafts, no guarantee of backward compatibility can be made and you should only use it for experimental purposes.
The wiki has some information about the current Fortran 2008 implementation status.