This can be quite simple to develop by putting together a jQuery tab container and iframes.

This could be further extended in a way that one single login would authenticate across all the WordPress installations. In this way we can manage the several installs from one single interface with full flexibility, i.e. we have exactly the same options as if we open separate windows and log into the installations.

Check out the example demo. Try going to Tab number 2 and logging in as user: admin / password: demo123

• http://ejohn.org/apps/learn – Do you think you know JavaScript? Well, see if you understand these code challenges. This is a interactive tutorial, that walks you through different examples which you can even run on the same site.
• http://jsbin.com – perfect to use in conjunction with the previous link. What you don’t understand just copy+paste here and try it out! This is a JavaScript playground so to say.
• http://tinyurl.com/yqua25 – in this video Douglas Crockford from Yahoo! talks about “The JavaScript Programming Language”.

If you’re coming from Actionscript then this link is a good read as well.