The release was necessary as with 1.0.5 some extensions were not working any more, 1.0.6 fixes this. Therefore: If your current extensions are working ok, don't upgrade (Version 1.0.7 might be in the pipeline :-) ).
http://www.mozilla.org/products/firefox/releases/1.0.6.html Escribió:
Restore API compatibility for extensions and web applications that did not work in Firefox 1.0.5.