Let's see, Mike Spille has done a fairly detailed comparison of HiveMind, Spring and PicoContainer. From a pure IoC (Inversion of Control) point of view, he likes HiveMind the most, which is heartening:
"All in all HiveMind looks to implement IoC in a very solid way, and generally only implement IoC and surrounding infrastructure (like configuration), and based on everything I've read is based on real project requirements (and I believe this shows). At the same time, some bits of HiveMind still seem a bit rough and appear to need polishing."
Meanwhile, Matt Raible has previewed his slides for his ApacheCon talk comparing web frameworks (here's a PDF link). He critiques Tapestry's documentation ... does nobody get that I spent most of a year of my life working on the Tapestry documentation ... beg, borrow or buy a copy, but don't claim there isn't documentation or good examples. Meanwhile, the community is creating its own sets of tutorials and you can find them all on the Wiki. Matt has a copy of the book but hasn't ready it yet, and I find that unfair.
Then there's the statement about Tapestry being impossible to test. That is simply not true, but the very question obscures a more relevant issue. You can test the methods, but there really is no such thing as unit testing a web application. Remember, you are supposed to test behaviors, not methods, and behaviors of web applications (or GUIs for that matter) are emergent from many things besides the raw code.
Given that, you had better have a plan for integration testing your application. There's a number of open-source and proprietary tools out there for this purpose, though I have yet to find one that uses a simulated servlet container that can be effectively run from within a unit test suite without any external requirements or servers.
For a servlets or Struts application, I have very, very little confidence that the application as a whole works, even if individual methods are tested and work. There's so much else that can go wrong. Tapestry is a much safer bet (because so much of the machinery is general purpose and tested) ... but still, what you are mostly testing in any kind of web or GUI application is that all the bits and pieces are configured correctly and hooked together just right ... things that don't show up in unit tests.
The best course of action for any kind of GUI is to embrace a proper separation of concerns and move important logic out of the presentation layer and into a more test-friendly environment. In Tapestry terms, keep those listener methods really small, and delegate out as much logic as possible into business objects. This will be a snap in Tapestry 3.1 ... just move all the logic into HiveMind and have the HiveMind services injected into your pages and components.
Matt does see something of worth in Tapestry:
"After working with Tapestry and JSF, I can see how component-based frameworks will be the wave of the future. I think as you develop more and more components, the code you write becomes less and less."
I maintain that this is much more dramatically true for Tapestry than for JSF, and Tapestry 3.1 will extend that difference. Further, I think Tapestry is the wave of the now. Anyway, look for the sparks to fly when I sit in on Matt's session at ApacheCon!