This month, I'm making a new dist under a different URL specifically for pre-release testing. If you want to test your project or library against the next update of Quicklisp, this is for you.
The test dist is called "qlalpha". It's available like so:
(disable (dist "quicklisp"))
(install-dist "http://alpha.quicklisp.org/dist/qlalpha.txt" :prompt nil :replace t)
From then on, all updates will pull from the "qlalpha" dist, rather than the main "quicklisp" dist. You can use it with ql:quickload to load and test Quicklisp libraries.
To switch back:
(disable (dist "qlalpha"))
(enable (dist "quicklisp"))
If you have any questions about how this works, or have any feedback about things that look likely to break in the next update, please feel free to discuss it on the Quicklisp mailing list.