Yeah, you heard right. Just a few days after the mozilla team released firefox 1.5.0.5 to the public a new release hits the mozilla ftp site and will be available on the webpages soon. Firefox 1.5.0.6 can only be downloaded from the offical mozilla ftp site as of know. As always there are not many information regarding this release, just a short note that the windows media player plugin stopped working on some sites with firefox 1.5.0.5.
“1.5.0.6 is a respin of 1.5.0.5 which is to address the external protocol handling regression.” Take a look at the following website which holds at least some information regarding this new release of firefox. (mozilla wiki for firefox 1.5.0.6)

Firefox 3 Release Candidate 2 released
Firefox 3.5 RC3 Released