The new June CTP of the Atlas Framework (internally known as build M2.2) finally features Dynamic UpdatePanels. Additional several bug fixes have been included. UpdatePanels can now be added dynamically into the page at runtime! This opens up a number of scenarios including UpdatePanels inside templates of data-bound controls, UpdatePanels in user controls used as WebParts etc.
Nikhil Kothari posted an great entry about the new Atlas build here, check it out!