The nightlies are generated twice every day. There are several packages:
core (formerly "rewrite") [download]The Python Wikipedia Robot Framework is a collection of tools made to fit the maintenance need on Wikipedia, but it can also be used on other MediaWiki sites. recent changes
Downloadspywikibot package directory.
Also it's possible to download one week old version of core: directory.
compat (formerly "trunk") [download]The older version of pywikibot which is not being supported anymore. recent changes
Downloadspywikibot package directory