I wasn't sure to write this as a "church websites that use blog software" or "church websites that have syndication feeds" since they're pretty much one and the same.
Here's a list of the ones I know about, in alphabetical order by state, province, or non-state federal district whose tax paying citizens have no voting representation in the Congress.
Unitarian Universalists of Petaluma, California (Blogger, for updates) '
Universalist National Memorial Church, Washington, DC (Movable Type)
Unitarian Universalist Congregation of Central Nassau, New York (Blogger, for updates)
Long Island UU News (twelve congregations, unknown CMS)
Later. Ah, it was rather rewarding to see a bunch of the above added to UUpdates.net as a cluster!