Apple, no matter what kind of company you or I may think it is, sure has some good software artisans working for their OS X team.
It's nice to be able to just start using svk without worrying about installing it.
I started using it, then realized I hadn't installed it yet -- but it was working. which svk told me that it was in /usr/bin/svk, which tells me that it was installed with the rest of the system. Nice!
Out of the corner of my eye, I noticed that there was a process transferring a lot of data at a sustained rate. A glance at Activity Monitor showed that it was the Apple software updater.
A few seconds later, it told me a new update for Leopard was available. I went for it.
Having read reports in the past of isolated problems with upgrades in the 10.4 series, I anxiously waited: Soon, I'll invest in a matching external drive, but at the moment, I keep backups of important files and projects but not my entire machine.
Thankfully, the upgrade process was smooth and went rather quickly. The more-opaque menus are a nice touch right away. I'm sure I'll discover more as time passes.
I'm back on the OSX platform, using Leopard, even. After a four-month absence, all of the keyboard shortcuts are coming back to me quickly. (The most disruptive I think is the distinction between switching between apps and switching between different windows of the same app.) I'm still within the first 24 hours of installing software and making it "home".
One of the pieces of software I needed to install was Mercurial. I quickly found out that, like many tools ported from elsewhere in the Linux/BSD/etc world, there is more than one way to install the same thing. :)
This is the easiest method, because, if you're using Leopard, it's one download and one package installation away.
http://mercurial.berkwood.com/ is a great resource. Scroll down past the Windows section and you will find instructions for Tiger users who haven't yet installed Python 2.5.1. Following that, you will find prepackaged installers for Mercurial, including recent fixes beyond the 0.9.5 release version.
Download the ZIP file you want, open it to extract it (Safari does that part for you), then open the installer (you can right-click in Safari then choose Open). Follow all the usual steps.
Now you can open Terminal and run hg --version to make sure it's installed. Running which hg should return /usr/local/bin/hg for this type of installation.
This method is a little more involved, because you need to first download and install MacPorts, which involves making sure you have the latest Xcode installed. You may have already installed such things if you are a "power user".
Once you have MacPorts set up, run sudo port -v install mercurial from within a Terminal window. It takes several minutes for it to download and install all of the prerequisites that it needs.
When it's done, as noted above, you can use hg --version to make sure it's installed. Running which hg should return /opt/local/bin/hg.