James Governor likes the usage numbers being reported for Sun's app server software:

Go buy some stock? The evidence is coming together in some interesting ways.... and if Sun's Java Enterprise System app server has momentum, anything can happen.

In the accompanying data, Sun's market share has jumped up to almost 20%, which does look good. However, that may not mean much revenue:

Download a complete enterprise-class solution -- Solaris 10, Java Enterprise System, development tools, desktop infrastructure and N1 management software -- at no cost, no kidding.

You only pay if you want support. There was an article on the uptake of support licenses for JBoss awhile back, and it wasn't encouraging:

Problem is, most people just take the free stuff and run. Only 3% to 5% of JBoss customers buy support contracts.

Which is one of the reasons that JBoss ended up selling out to RedHat - the ongoing development costs simply weren't being met by those paltry incomes. So let's look at the app server and OS for Sun, shall we? Schwartz has made Solaris free and open source, and championed it running on x86. So even if I decide to run Solaris instead of Linux, I still don't need to pay Sun a nickel. The same goes for the app server. This is the ideology of free masquearding as a business plan, and I doubt that it will end up happier for Sun than it did for JBoss.

If you give it all away for free, you can't make it up in volume.