DrupalConDC Field API at Drupal 7
Field storage is pluggable - take a look at a 4 GB blob about to go in, and send that to some other storage rather than a MySQL database, and let Drupal know you've taken care of it.
Fields - base types.
Bundles: Mostly equals content types, but the same concept (article has these fields, blog has these fields) but it can be applied to other objects.
Field types - a field attached to a particular bundle.
Allowed values functionality removed and replaced with list.
The User interface is not in core yet. I was initially opposed, thought it should stay contrib, but now I agree it should go in core.
It's all documented now!
Can simply add a field
File handling should be field.
Taxonomy should be field-like.
There will be nothing special about a node. It will just be how we think of content (the node itself, the fields can be anywhere) that lives in the local Drupal database.
It was very very difficult to deal with CCK programatically before. Now there's an API.
Module developers will use fields for storage because it's so much easier.
Profile module won't die, it does a lot more-- it will switch to using fields, but it will continue to exist-- it adds the tabs to the user account, it lets you.
A module in your project that controls the evolution of fields
see schema version
put upgrade hooks into your project
schema updates for x and y
this requires you manage all your fields in code -- which you generally need if you want a complex development, staging, production workflow.
Implementing a field type, can you say that imagefield is derived from filefield?
That's in code, by developers.