Hi all,
AuthManager is coming soon (see the recent wikitech email [1] for more details), which means mobile login and registration (whether API- or specialpage-based) will have to adapt to the increased flexibility of the authentication system. The new web-based login page uses HTMLForm to generate the fields (the vform flavor, for now); I'm hoping that works acceptably on mobile.
Unfortunately none of us working on AuthManager have a lot of experience with mobile design, nor have access to a large variety of devices, so we would very much appreciate any help with testing, or pointers on what to look for. If you are interested, the current test site is at
http://authmanager.wmflabs.org/ with a mobile version at
http://mobile-authmanager.wmflabs.org/ .