Fast Track to My Sidebar

Fred posted yesterday about the brilliance of the MySpace "add" feature on their music player, and how most widgets lack the immediacy of this feature.

Most of them provide a landing page, then they have a conversion issue.  Eventually you wind up with some embed code and then its all about hacking your template.   There's no universal "add this to my sidebar/blog" etc.

Or is there?

XML-RPC is what allows services like Flickr to autopost my Moblogged photos directly to my Typepad blog.  All I needed to do was to tell them where to post it, give them my password, and poof, automatic.

Can the same thing be used for my sidebar?

How hard would it be for some social widget to have a "Get this" link that pops up a window, lets you configure, and then all you have to do is give them your blog password and poof, its there up at the top of your sidebar.

Is this possible through XML-RPC?