When creating new User in the admincentral (Menu 'Security'=>'Users', then invoke 'New user'), user is created as untitled, which seems correct.

According to forum thread
http://forum.magnolia-cms.com/forum/thread.html?threadId=30ce8ee0-9c9f-42c1-b02f-3a668bb96a59&page=1
then a node 'acl_users' should be created under the new users node, allowing to change own properties.

The user is created, but no 'acl_users' node is included.
Debugging does not showing MgnlUserManager.createUser(String, String) being invoked.

Renaming the user to 'user1' doesn't add the missing 'acl_users' node, according to export-XML.
Adding groups (editor) also doesn't fix the problem.

When logging-in as the user1 and editing own settings, the dialog is empty when loaded, save leads to empty page.
On loading the dialog, the logs show an error:
2011-06-07 10:36:38,473 ERROR fo.magnolia.module.admininterface.DialogMVCHandler: can't read content to edit
info.magnolia.cms.security.AccessDeniedException: User not allowed to Read path [/admin/user1]
at info.magnolia.cms.core.Access.isGranted(Access.java:64)
at info.magnolia.cms.core.DefaultContent.<init>(DefaultContent.java:117)
at info.magnolia.cms.core.DefaultHierarchyManager.getContent(DefaultHierarchyManager.java:236)

after submit a npe is logged, caused by the node not read previously to the password dialog control:
2011-06-07 10:36:38,488 ERROR info.magnolia.cms.servlets.MVCServletHandlerImpl : can't call command: save
java.lang.NullPointerException
at info.magnolia.cms.gui.dialog.DialogPassword.validate(DialogPassword.java:98)
at info.magnolia.cms.gui.dialog.DialogControlImpl.validate(DialogControlImpl.java:620)

Can be reproduced perfectly on current demoauthor-instance (althought the 'eric' demo-user is able to change own properties).