A new report by traffic metrics firm Hitwise shows Facebook’s share of US Internet traffic hit an all time high on Christmas Eve 2008 at 2.18% of all US Internet visits.

While the report doesn’t show how total Internet visits trended on that day relative to the rest of the year, it does show that Facebook’s share of US Internet traffic on Christmas Eve was 50% higher than its November average, and 50% higher than it was on Christmas Eve 2007.

Why the spike in traffic? Many people are home from work or visiting relatives and have a lot of time to connect with friends on Facebook. And as we saw with the the plethora of popular Christmas applications on the Facebook Platform, many people used applications to send holiday greetings this year as well.

In 2008, it took 6 months for Facebook’s share of visits to surpass the mark it set on Christmas Day 2007. We’ll see how long it takes in 2009!