StumbleUpon broke into the top 10 of the most visited social networking sites this past November, exceeding MySpace for the first time ever.

This is the first time MySpace has failed to rank in the top 10 social networking sites, according to the stats compiled by Experian Hitwise.

Experian analyst James Murray said StumbleUpon owes its top 10 position to MySpace’s continuing decline rather than a boost in its own traffic.

MySpace’s traffic has been in decline for the last three years. Since November 2008, its market share of visits to the Social Networks and Forums category has fallen from 5.8% of all visits to just 0.36%, whereas visits to StumbleUpon’s have increased by 44%.”

Despite numerous redesigns, MySpace remains to be seen as a place for unsigned acts and musicians to promote themselves. Now it faces strong competition in this area, not least from YouTube.

The top 10 for social networks is still dominated by Facebook and YouTube, which achieved 52.6% and 23.6% of visits to social network sites in November respectively. Twitter came in third with 3.1% of visits.

But it’s not all good news for Facebook, which saw a 5.7% drop in its share of traffic year-on-year.

Experian also looked at the traffic in November for search engines, which is predictably dominated by Google with 91.1% of searches. Microsoft came in second with 3.8% of search traffic.