New Application Advice

I think it's time for me to learn more things about RoR and finally move on to Rails 1.2. So, I've got my InstantRails 1.6 ready to go and am looking at an application to use for playing with.

I would like to design something like MSDN or, more appropriately, like the PHP documentation website (http://www.php.net/docs.php) with basically content from manuals (API docs), community content (for my engineers to add in more stuff), developer blogs, wiki for ad-hoc documentation, developer forum, and user accounts for personalized features. I think I'd also need to use things like tagging of content, etc. I would ideally like to use the best tools for the best job (for example, I'm currently using YaBBS for a developer forum) and might have to look at ways to integrate these together if required. Either way, I think it's a useful project and I'd learn quite a bit along the way.

I watched the screencast for Hobo and was quite impressed. Are there many people using it? I ask cos it seemed that the documentation is a bit incomplete though the blog/ wiki seems quite responsive. I imagine I may need to trouble the group a bit if I choose to use it.

What do you guys think?
Cheers
Mohit.