Effective on the [U.S.-formatted] dates listed below, IBM will withdraw support from the following product releases licensed under the IBM International Program License Agreement:
 
5724-E70  6.5.[x]         4/30/09     IBM Lotus Notes and Domino
55724-E89  6.5.[x]        4/30/09     IBM Lotus Enterprise Integrator

This means that 6.5.6 is the last maintenance release for the 6.5 codestream.  Mainstream technical support for Notes/Domino 6.5.x (as well as LEI 6.5.x) will end on April 30, 2009.  Support extensions are available for up to two years following that date (through April, 2011). The Notes/Domino 6.x codestream first shipped in September, 2002.

Original IBM Announcement (PDF File)