One feature you may not even be aware exists is the ability to change your Windows Live ID e-mail address and have all your associated accounts and contact list automatically updated.  This isn’t a new feature by any means, but it’s always been placed subtly in the Live ID/Passport web site so most people wouldn’t discover it unless you were really looking for the feature.  If you want to see where it currently is, sign into the Windows Live ID account site, and just note the ‘Change’ link next to your e-mail address.  Note: if you don’t see the Change link, read on.

There have been two long standing issues with the process.  The first is that you can’t change Hotmail.com, MSN.com or Live.com (including all the localized country versions there of) to another address as those domains are “reserved” (note that Microsoft has provided the ability from time to time to switch to one of these reserved domains however).  The second is that you typically needed to remain offline for a good few hours for the modifications to all your contacts’ contact lists to your new address.  Before about a month ago, I was recommending to people to just make the change before shutting down for their day, and everything would be ready when they woke up.

Broken
However, beginning with this latest update to the “Wave 3” Live web sites, this feature has become quite unreliable and in general, your Messenger contact list will never be updated.  So although the web site currently claims all you have to do is wait 48-hours, you’ll end up with a contact list of offline contacts even after the wait.  Since your contacts won’t have your updated address on their contact list, they’ll see you as offline too.  You end up in a limbo state.

What to do
If this has happened to you, the easiest fix is to return to the Live ID site and switch your address back to the previous one.  After signing back into Messenger using the old address, your contacts will all be online again as per normal.  You can then try again hopefully when this problem finally gets fixed.

Unfortunately this fix won’t work for those who have switched to a live.com (or localized version there of) address.  For those people you can ask your contacts to manually add you to their contact list and you’ll immediately appear online to each other.

Additionally, if this happens to you, you’ll want to let the Windows Live ID support team know, as they do eventually escalate it up to someone to be corrected.  You can get to the support form by heading to the Live ID support help section, click the link to any of the articles on the side, and then choose the ‘Get more help’ link at the bottom right.