A recent cnet article suggests that Ubuntu is eating other distribution's lunch. In particular, one distribution is reported to be falling apart: Gentoo. Gentoo was very popular among my friends at the time I adopted Linux, but from what I've seen, the project fell apart as developers were unable to come to consensus or resolve conflicts.
The article cites Google Trends as evidence of Ubuntu rocketing off to outer space while Gentoo stagnates. I'm reminded of the current 5-a-day discussion; there's a certain amount of danger to blindly trusting metrics. This Google Trend shows "Ubuntu" approaching "Dell":
More Here