I had problems registering at a Xaraya site the other day. It was St.Egos site, The Ivory Tower (a recommended bookmark if you're a Xaraya user or developer). It's a problem that's since been fixed. St.Ego makes a very good point at the end of that post, about how easy it is for developers to overlook such features. I know I'm guilty of it myself, often I find I've written a new function, updated here on site, and then found that it doesn't work for everyone, usually due to privileges.
It's a good reminder that when testing with Xaraya, you really need to go through every possible access level and make sure your site functions and displays correctly, from anonymous users right through to admin (it's all too easy to forget you have admin privs when you're developing or template editing)
Whilst over at the Ivory Tower, I also spotted a post about twittering from xaraya This site's sorely lacking in the social bookmarking and interaction department, and is something I'm looking to change, so that little snippet will come in handy.