It's not news that Google rewrites page titles in selected situations; John Mu has described these in the Google forums:
but we're seeing evidence of what I would call a bug in the algorithm:
1- Google is choosing titles from the DMOZ archive of _different_ pages, when those pages are 301'd to a current page
2- Google occasionally truncates the title down to just our domain name
Neither of these approaches give the search user more or better information. In fact, both are producing demonstrably worse results than using the the title in our <title> tag.
Here's a clearer example of #1:
a) create page X with title "foo"
b) wait a few years, until DMOZ indexes page X
c) create page Y with title "bar"
d) deprecate page X; 301 it to page Y
Oops, Google shows title "foo" for page Y ("bar").
[edited by: tedster at 6:03 pm (utc) on Jun 3, 2011]