I'm hoping to start a discussion on the subject of tabbed panel content because the Panels Tabs module is looking for a new maintainer and has not been ported to D6, and I'm getting requests in the Quick Tabs issue queue about integration with Panels (see for example #353173: Absorb panels tabs module? and panels 2 as tab content). I don't have a huge amount of experience with Panels myself and am not sure what form Panels integration in Quick Tabs should take if it proved to be something worth starting. What Quick Tabs does currently is allow you to create blocks of tabbed content (blocks, views, nodes, and other quicktabs) which are either all loaded on page load or else via ajax on tab click. Panels Tabs, on the other hand, is a style plugin for panels so it comes at the issue from the complete opposite direction.
I'd ideally like to get some feedback from merlinofchaos and Wim Leers to see what they think about the general issue of tabbed panel content and whether Quick Tabs could play a part in achieving this.
EDIT: I meant to add that it would also be good to hear people's use cases for this type of functionality.