Does the StackOverflow API offer some way to authenticate a user? I am wondering if the API supports logging a user in so that they can write to the system.
Yes it is read-only, you can't authenticate a user in any way.
Version 1 is read only. Coming up with a solid API is hard enough without adding writing and authentication to the mix. For the initial release, it’s a read-only API. We’ll take on the much more challenging problem of writing (and authentication) in v2.