A bug was reported on the forums that affects current 1.4-beta2 users. When you store custom entry properties for an entry (using the entryproperties plugin) those will not get remembered properly, when you re-edit the entry. We consider this to be a serious bug in the problem, so all 1.4-betatesters using this plugin should fetch an updated 1.4 snapshot.
Since the final 1.4 version will be out in a few days, we do not think this warrants an extra 1.4-beta2 release, as the current Snapshots contain the same files.
Other things that have been added to the current 1.4 release tree include an SMF importer, a fix for remembering cookies longer, a new %parentname% permalink shortcut for category permalinks, adding an autocomplete=off attribute for the password-fields so that Firefox does not store the user password into unrelated password fields, more documentation and ChangeLog links to plugins and yet another fix for properly counting trackback/comment counts.