The biggest mistake I made in Leonardo was making "foo" and "foo/" mean the same thing. I don't mean directing one to the other with a 301, I mean returning the same content at two different URLs. If you add the fact I listened on both jtauber.com and www.jtauber.com, it meant that every resource had 4 distinct URLs.
That's now fixed: www.jtauber.com redirects to jtauber.com and "foo" is redirected to "foo/".
Unfortunately, most of the del.icio.us bookmark counts I include at the bottom of each page are now effectively reset to 0. While 164 people had bookmarked "poincare_project", none had bookmarked "poincare_project/". Even though the former now redirects to the latter, I've effectively split the vote between past and future bookmarking of that page.
As far as I know, del.icio.us never heeds 301s and updates its database accordingly. Google Reader doesn't seem to either, judging by the continual checking of "/atom/full" in addition to "/atom/full/".
The original post had 12 comments I'm in the process of migrating over.