Thanks Jerome.
I updated the administration app, as you suggested, only maybe not as
carefully as you suggested :)
I should learn to read instructions.
I did update the group pages. That, as you predicted, went OK apart from the
XWikiAllGroup. Can you run the script to restore that for
http://patternlanguagenetwork.myxwiki.org/ ?
As a side note, it would be nice to have an option to perform bulk
operations on a group's member list, by using a list of all members with
checkboxes. Not instead of the current interface, but in a addition.
One more thing that seems to be broken is the "smart table" I use on several
pages, e.g.
http://patternlanguagenetwork.myxwiki.org/xwiki/bin/view/Patterns/
I don't think I customised the XWiki.XWikiPreferences, unless I did it
unknowingly..
2009/2/11 <users-request(a)xwiki.org>
  From: Jerome Velociter <jerome(a)xwiki.com>
 There should be no problem if you take care. If you don't want to
 upgrade the whole XE, you can take just the administration application
 from here
http://maven.xwiki.org/releases/com/xpn/xwiki/platform/applications/xwiki-a…
 to solve this issue
  - specifically, it says that all group
memberships will be broken. We 
 have a
  lot of groups with a lot of users, is there any
migration script I can 
 use?
 Just make sure you exclude the group documents (XWikiAdminGroup and
 XWikiAllGroup) from the list by un-checking their boxes. Beware if you
 forget this is not that easily reversible (but your XWikiAllGroup can be
 re-created by script, though, you'll have to do the AdminGroup manually).
 For all other groups you created yourself, you have nothing to worry
 about, they are kept safe.
 What the upgrade will do is update the group sheet
 (XWiki.XWikiGroupSheet) so that it asks for the proper javascript
 library to be loaded.
 Don't forget to exclude XWiki.XWikiPreferences, too, as you probably
 customized it.
 Jerome.