If I recall correctly, getfirefox.com was the de-facto site because an individual blogger had owned and been using firefox.com. Mozilla was finally able to acquire the firefox.com domain and for a time, offered a free redirect to the original blog. I also tried to find a link to corroborate the history but was unable to do so, just the WHOIS data below. Please feel free to correct me if I'm wrong.
WHOIS data for firefox.com says it was created in October 1998, four years before the Firefox project was started in 2002, and six years before the 1.0 release in 2004.
WHOIS data for getfirefox.com says it was created in April 2004, seven months before the 1.0 release.
