I would love to be able to use XPointer in my URLs. Ideally it would also be made to work in text/html documents too.
Please see http://www.w3.org/TR/xptr-framework/
Confirmed as an enhancement request.
Chromium team was recently asked for this feature in the form of enabling scrolling cross-domain iframed content into view.
See the whatwg thread starting here: http://lists.whatwg.org/htdig.cgi/whatwg-whatwg.org/2009-April/019145.html
My summary of that thread: Gecko added support for XPointer on XML documents in 2003 and removed it due to lack of adoption from web developers. It's unclear why web developers didn't use XPointer in Firefox, but it's at least partially because it was never implemented for HTML/XHTML pages. XPointer is XPath based, but it's conceivable that once we have XPath support, we could reasonably add other schemes like "css" if we wanted selector-based matching.
There was some concern that this somehow increases the ability to do clickjacking, but I really don't buy the argument that this makes clickjacking attacks more effective.
Here is a simple use-case that I wanted to use this evening: linking to the 24th paragraph tag of the 23rd blockquote tag of an HTML document on the Web: