The Shrinking Long Tail - Top 10 Web Domains Increasing in Reach: It does appear that the top 10 web properties are claiming proportionally more page views in 2006 than in 2001.
The impact of the Long Tail can still be felt strongly on the content creation side, on sites like MySpace and YouTube. So in one sense you could argue that The Long Tail has had an impact on the top 10 domains after all - in terms of who is creating the content. But the fact is that those properties are still owned and operated by big media (News Corp and Google in the above two cases). So in that respect, and according to Compete's stats, the top 10 domains have more reach now than 5 years ago.