Stripes is the main Java web framework choosen in the company i'm actually working in.
It is used on many websites here, including medium sized projects like the french Renault and SFR websites (both ~40 people teams).
Everybody here quite like this framework that integrates nicely with Spring (IoC, Security).
As ScArcher2 said, you can come to the IRC channel #stripes on freebode, it's active with an average of 15 people here (mostly USA business hoursi noticed), including Frederic Daoud who wrote the Stripes book and Ben Gunter, Stripes commiter, and some other people that will be able to give you some advises or friendly discussions.
Stripes documentation is not exhaustive (imho) but it's easy to look at the framework's code and see how it works internally. However if you need help to do something you will find that on the irc channel
The bug fixes comes relatively fast, not like some other projects like Hibernate where some bugs can remain for many years.
Btw if you really like simple Java web frameworks, you should also take a look at Play!