DateTime itself has no sensible parser. There is DateTime::Format::strptime, but after looking at its code, I'm not sure anymore that that's a sensible solution :-)
dragonchild,
You may think it is a ridiculous requirement but I disagree. I am not going to defend the position but instead set it aside to see how well DateTime fits the other criterion. Since DateTime doesn't even have a parsing method that I can see, let's assume you meant DateTime::Format::DateParse which isn't part of the DateTime bundle.
Written in pure perl - pass
Is not part of a bundle of other un-wanted modules - pass since the bundle is quite small
Well documented - fail
Provides the ability to control behavior when multiple dates are possible - fail from my perspective (strptime)
So it fails 2 of the remaining requirements, the same as Date::Manip, but also doesn't satisfy my ridiculous requirement.