This tutorial covers how to add Glow and Glare effects to your object lights in Blender 2.5 using the Compositor.
[EDIT]:See my second tut for a BETTER ALTERNATIVE to PASS INDEX --> vimeo.com/13508778)
The final .blend file can be downloaded here: http://www.megaupload.com/?d=C49JRIHU
It includes the featured scene in the video thumbnail.
This is a combination of 2 tutorials i have seen,
And the 2.49 version Screen-Shot(Slightly Different) is available in the Blender Artists Forums: http://blenderartists.org/forum/showthread.php?t=189699&page=3