I have my account linked with 5 Stack Exchange sites. When I visit stackexchange.com, I can see my nickname in the header (lobster1234 | log out | chat | meta | about). However, when I click on my nickname, I get a 404. Not too big of a deal, but thought of asking it here in case this is impacting more users. Also, this works fine when I click on the nickname on the sites that I've linked with.
There are still some glitches related to syncing GUIDs across the network. For now, I've updated your stackexchange.com GUID, so the link is fixed for you now.