I appreciate that this is hard to do right - but if you provide the user a way to edit the results (say, a pop-up window to edit the name if it didn't guess right) and still guess "right" for most cases... of course it's the guessing that's tough.
It's easy to say "don't do it" when looking at the problem theoretically, but sometimes circumstances dictate otherwise. Having fields for all the parts of a name (title, first, middle, last, suffix, just to name a few) can take up a lot of screen real estate - and combined with the problem of the address (a topic for another day) can really clutter up what should be a clean, simple UI.
I guess the answer should be "don't do it unless you absolutely have to, and if you do, keep it simple (some methods for this have been posted here) and provide the user the means to edit the results if needed."
