There is a NPE in AnonymousContext (trunk, fresh setup) when accessing Magnolia.
/magnolia or /magnolia/.magnolia (where magnolia is the instance/context):

Servlet.service() for servlet default threw exception
java.lang.ExceptionInInitializerError
at info.magnolia.cms.filters.MgnlContextFilter.doFilter(MgnlContextFilter.java:35)
[...]
Caused by: java.lang.NullPointerException
at info.magnolia.context.AnonymousContext.createAnonymousSubject(AnonymousContext.java:121)
at info.magnolia.context.AnonymousContext.<clinit>(AnonymousContext.java:54)
... 19 more

or

Servlet.service() for servlet default threw exception
java.lang.NoClassDefFoundError
at info.magnolia.cms.filters.MgnlContextFilter.doFilter(MgnlContextFilter.java:35)
[...]
at java.lang.Thread.run(Thread.java:613)

no cause, maybe this is caused by something different

Commenting out assignment of anonymousSubject and anonymousUser and the listener lets one log in - but AdminCentral produces more exceptions.