For those folks who have requested MagCloud publisher invitations, thanks! Just wanted to let everyone know that we've received a few ;-), and are churning through them as quickly as we can. We're not running a secret MagCloud Idol competition with a panel of judges, so if you haven't heard back yet there is no need to worry that we've deemed you unworthy. We're simply trying to ramp up reliably and predictably; we're accepting invite requests somewhat randomly to try to sample many different types of publishers, with a bias toward first-come, first-get.
For all our new Beta users, publishers and non-publishers, thank you on behalf of the MagCloud team. Never have I seen such supportive bug reports :-). Can't tell you how much that helps as we're stomping the bugs.
If you have an existing account and want to use an invitation to upgrade it to have publisher capabilities: when you click on the accept invitation link, look for the link highlighted below.