If possible I would also like to know the answer to this, the exact same is happening to me. Vendor text works, images don't.....
Sun GlassFish Enterprise Server v2.1 (9.1.1) (build b60f-fcs)
java version "1.6.0_17"
Java(TM) SE Runtime Environment (build 1.6.0_17-b04)
Java HotSpot(TM) 64-Bit Server VM (build 14.3-b01, mixed mode)
I believe it references this documentation:
http://java.sun.com/developer/technicalArticles/J2EE/jws-glassfish/part3.html
The following should be the relevant sun-application-client.xml file, with the appropriate images located under appClientModule/images (using Eclipse) in the Application Client that is included in the EAR.
META-INF/sun-application-client.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE sun-application-client PUBLIC "-//Sun Microsystems, Inc.//DTD
Application Server 9.0 Application Client 5.0//EN"
"
http://www.sun.com/software/appserver/dtds/sun-application-client_5_0-0.dtd">
<sun-application-client>
<java-web-start-access>
<vendor>images/icon.jpg::images/splash.jpg::My Company</vendor>
</java-web-start-access>
</sun-application-client>
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