Fairly late to the party on this discussion, but this captured my attention:
On Tue, Sep 29, 2009 at 11:35 AM, Curt Sampson
This may be somewhat anecdotal evidence, but I disagree with both of your statements here. I've rarely known anybody to use Java cross-platform in a non-trival way, barring a few major GUI-centric projects such as Eclipse. (I've far more cross-platform use of Haskell than Java myself.) And I know of nobody who did anything serious with download-execution of Java.
I agree with the download/execution part of this, but I'd be willing to bet that it is incredibly common for Java developers to write and test code in an environment very different from the actual deployment environment. With Java, it requires no special forethought to write an application on a Windows or Mac laptop, be able to run all the unit tests, etc., locally, and then deploy the production application to a Linux or Solaris or *nix server (or a combination) without any required recompilation. This is a pretty powerful selling point for the JVM as a target platform, and everywhere I've seen Java used, it's been taken advantage of.