如何将描述性文本解析为DateTime对象？

Are there any existing libraries in existence that will parse a datetime from a plaintext phrase? I'm looking for something similar to Remember The Milk or Outlook, where the user can enter "next tuesday at 6pm" or "tonight at 7" and the library can spit out {4/28/2009 18:00:00} or {4/25/2009 19:00:00}. I'm considering writing my own, but I'd rather use/contribute to something already in existence.Are there any existing libraries in existence t