From Greg Wilkin's Jetty Improves in Netcraft survey (again):
As with most open source projects, it's very hard to get a measure of who/how/where/why Jetty is being used a deployed. Downloads long ago became meaningless with the advent of many available bundling and distribution channels. The Netcraft Web Survey is one good measure, as it scans the internet and identifies which server sites run. In the results released April 2008, Jetty is identified for 278,501 public server, which is 80% of the market share of our closest "competitor" tomcat (identified as coyote in the survey). Jetty is currently 12th in the league table of identified servers of all types and will be top 10 in 6 months if the current trajectory continues.
If you look at the Netcraft numbers, you might also notice that Resin isn't far behind Jetty. If you look at the Indeed Job Trends graphs for the three, there seems to be some interesting information there too. The first graph is absolute and the second is relative.
If you're using Spring Dynamic Modules to deploy a web application, which server do you think is better? Both Tomcat 6 and Jetty 6 seem to work just fine in Equinox.