I've just installed it on Leopard (Mac OS X 10.5.2). After I double click it, it displays the message about viewing its windows through X11, then, after I click on OK, it goes away. What gives?

You might try searching the forums for info on installing and running Inkscape on a Mac. There are numerous topics, and you may find a solution already posted.

Refer to the sticky topics (viewforum.php?f=4) for where you may find the answer.

Thank you both, brynn and microUgly! I've followed your advice and am learning about the versions of Quartz and what-have-you.

It turns out, inkscape complains if you try and run it from anywhere but /Applications. I had put mine on the Desktop, so it quit on launch.