You can currently (it may change) find a copy of 3.0.17 at:
all-older downloads
The only issue listed as fixed is:
Fixed a problem with how updates were being presented to users.
As noted by iJohnE, there are no security updates.
Release notes are located at:
release notes
UserAgent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.16) Gecko/2009120208 Firefox/3.0.16 GTB6 (.NET CLR 3.5.30729)
