The console reports the following resources to be missing whenever I try to use the Neptune theme in Ext 4.1.0 Beta 1. I can confirm that the zip file of 4.1.0 Beta 1 does not contain these images.

PHP Code:
GET 
http
://localhost:8080/app/extjs/resources/themes/images/neptune/tab-bar/scroll-right.gif 404 (Not Found)
GET http://localhost:8080/app/extjs/resources/themes/images/neptune/grid/loading.gif 404 (Not Found)
GET http://localhost:8080/app/extjs/resources/themes/images/neptune/grid/unchecked.gif 404 (Not Found)