Product Version = NetBeans IDE 6.9 (Build 201006101454)
Operating System = Windows 7 version 6.1 running on x86
Java; VM; Vendor = 1.6.0_20
Runtime = Java HotSpot(TM) Client VM 16.3-b01

Make a Java Application project that uses one of the built-in libraries (e.g. Beans Binding).  In the project properties enable Web Start.
Build the project.
The jars that end up in the dist folder are not compressed.  Since there is a high likelihood that the application will be delivered over the web, compression is most likely desirable.
There is of course the option in the "Packaging" section to compress the main jar.. however I argue that similar options should be available to compress library jars as well, since they are built-in the developer does not have the option of building thelibrary as a compressed jar in the first place, as they would for library jars that they create.  There are several possible options that might be useful for web deployment via Java Web Start  
- There could be options to compress library jars as well as the main jar so they download faster.
- There could be options to re-package libraries into the main jar (compressed) so there are fewer requests to the server
- There should be options to package  libraries automatically as "Extension Resources" so they can be more easily shared between applications and cached by Web Start.  When defining libraries, for example JOGL, there should be a way to specify the URL of the Extension Resource JNLP so it is automatically used for Web Start deployment of the application. (e.g. http://jogamp.org/deployment/webstart/jogl-core.jnlp)
-Pack200 and GZip options should be available. http://java.sun.com/j2se/1.5.0/docs/guide/deployment/deployment-guide/pack200.html

Perhaps enhanced Web Start support could be provided by optional plugins.