In reply to Thomas Ehrig.

This isn't necessarily low-hanging fruit. On a purely technical level, it should be easy, but there are other major considerations.

The first issue is whether WordPress.org should allow demos from a third-party site. There are security implications. That's a big can of worms that no one has really been prepared to open yet.

The second major issue is how this plays into the theme review process. New guidelines must be written (this won't be a small feat). TRT must cover those guidelines in the reviews, which will further slow down the currently slow process. To top all of that off, we'd need to figure out what to do when the demo URL is no longer relevant. We'd have to catch people doing nasty stuff after they've been originally vetted through their theme review.

What I'd personally like to see is a multisite installation run directly on WordPress.org for all theme authors. This way, there's some level of control on the WordPress.org side of things. Theme authors would get a demo blog that they'd be able to set up just for their theme.

What would make this even better is that theme authors could opt to have a basic set of demo content pre-installed. Another thing WordPress.org could do is allow theme authors to activate plugins from the plugin repo.