Ok, I gave this a shot... It didn't work. I'm confused though. I switched between the normal theme and Neptune. The images generate correctly for the regular theme. The slice command runs with no errors against the Neptune theme but no images are created.
Given the fact that they're not on the Sencha examples page either, I fear they may never have been created. This makes neptune practically unusable and a poor inclusion to the 4.1 release, especially after it was hyped so much.
It's been 9 months now, and the theme is included (4.1.1) as if it was meant to be used. But it's missing a lot of resources (possible examples that need these resources are conveniently not displayed in the Kitchen Sink example, making it look like it's a full theme).
Is this still going to be released? Either way I'm going to need to know, since this Neptune theme would suffice, but else I'm going to have to create my own. Then if creating my own theme is really as hard as it appears to be, I might have to rethink using Ext JS on the public side of our applications.
P.s. A warning placed on the Kitchen Sink example that the theme isn't presentable enough for a live environment is desired.