Hi Karl, looks like you figured out it was the wrong version.  I'll look into 
making an explicit check in the installer and work with the website people to 
see if we can clean that up.

Adding lcantey to nosy list

It turned out I had the version intended for osx 10.6 and I am running 10.5.8.

The installer should probably check the OS version and give a clear error
message, as the current operation is misleading and frustrating.

It gets especially frustrating since the Mercurial front page has one of
those "Download now" links that one would associate with easy, user
friendly, and trouble-free installation the likes of such as Skype or Firefox.

What URL does your package come from?

I downloaded mercurial by selecting the "download now" link from the main
mercurial page.  It said I need Python 2.4, so I followed the link.

I downloaded and installed Python 2.6.4 from www.python.org/download.

When I ran the mercurial installer, it complained:

---
You cannot install mercurial 1.3.1 on this volume.
mercurial requires Apple Python 2.6 to install.
---

I've already installed Python 2.6, but mercurial still refuses to install.