I asked ajshort (the module's maintainer) about NestedURLs about a week and a half ago in IRC.
Here's a copy of the log.
01[01:25] <joshual> ajshort: Being the maintainer, Do you have any caveats or advice for working with the nestedurls branch? I've just started looking into it and haven't been finding much info.
[01:25] <ajshort> sure
[01:26] <ajshort> 1) use the github version - i stopped developing in svn a while ago
[01:26] <ajshort> 2) alot of code uses $page->URLSegment to generate links, instead you should use $page->Link() or $page->RelativeLink(), $page->ElementName() for a CSS identifier
[01:27] <ajshort> yeah i havent written much documentation for it since its largely been a behind the scenes thing (i think)
[01:27] <ajshort> although merge back should be fairly soon :)
[01:27] <stuckinrealtime> joshual: I've got several projects deployed which use ajshorts wonderful magic. all i can say is works great!
01[01:28] <joshual> Thanks, without knowing number 1 in particular I would have been in for some trouble.
[01:28] <ajshort> heh
[01:28] <ajshort> github.com/ajshort/sapphire and github.com/ajshort/jsparty