Just found this very cool widget: PHP Code Widget
The normal Text widget allows you to insert arbitrary Text and/or HTML code. This allows that too, but also parses any inserted PHP code and executes it. This makes it easier to migrate to a widget-based theme but the fun part is, together with the Mobypicture plugin it enables you to include multiple Mobypicture streams in your sidebars. Just like I included the public stream.
Install both widgets and then include the same Mobypicture php code you would use to include the a Moby stream in a post or page.