User accounts

[eluser]pbreit[/eluser]
I'm a little confused. There's lots of discussion about user accounts, authentication, permissions, sessions, etc. but surprisingly little agreement. And little or no out-of-the-box assistance from CodeIgniter.

User accounts are pretty much standard on any web service these days and they all basically work the same way. This seems like a critical and straightforward feature of a framework like CodeIgniter. ExpressionEngine has user accounts, right? How are they implemented?

If I had to take a stab at some of the requirements:
- Registration
- Login
- Password recovery
- Session management
- User profile
- User specific web pages