One little thing before we get started. I've added FeedBurner flares to my posts and have noticed a distinct delay when the first post is rendered. Time will tell if my patience holds...
So there's a new CTP for the Atlas Control Tookit with a bunch of new controls and presumably some bug fixes and improvements. The bug I encountered previously, where TextBoxWatermark and AutoComplete could not refer to the same textbox seems to be fixed at least.
I notice the Accordion control is now a full-fledged control. It looks great. Transitioning 'twixt AccordionPanes is pretty snazzy and there are some nice configuration options on it. I tested it with my music player thingy and got it up and running with a minimal amount of fuss except for one little issue. I no longer seem to have direct access to any ASP.NET controls within the AccordionPanes. I can get at them if I navigate through the various Controls and GetAccordionPanes collections/methods but the controls no longer exist as variables in my page. Which is a bummer because it means the other extenders I've added to the controls within the Accordion don't work anymore.
** UPDATE ** The workaround (and I hope they consider this a workaround) is to ensure your AutoCompleteExtender is declared before the CollapsiblePanel.