I apologize that this isn't going to be a well-formed report, but I've run out of time and I don't fully understand some of the code, so I'm not sure I'd be submitting the right patch anyway. The gist is that MarsEdit 1.1 (a popular Mac blog editor) is sending dates like 20051210T08:28:40+0000, and that's not accepted by the overridden XMLRPC::Convert::dateTime in lib/xmlrpc_fix.rb. There seems to be a newer version of that method in ruby (but not the ruby on my machine), but it doesn't work as-is on my system. I took a stab at hacking it up anyway. I'm just going to point to my blog entry at http://www.secondhandlederhosen.com/articles/2005/12/10/why-software-is-not-there-yet where there is a longer writeup.

Presumably it's a good idea to update this method in general, because it only accepts a subset of ISO 8601 (no timezone offset or Z). Also, if ruby comes with a better one, it would be bad to keep overriding it with an old version.