Two documents have been added to Firebird documentation area
How the cache works in Firebird :
That is based on information Ann Harrison supplied on the firebird-devel list a while back. She has permitted me to document it and make a manual out of it.
And Firebird Internals :

As Firebird approaches the final 2.5 release, a new campaign is born to help increase Firebird’s visibility and awareness.

I’d like to clarify some facts about Firebird and Firebird Foundation. I think right now is a correct time to remind how all these things are organized, because some messages about "crisis, firebird's death, low finances" and so on being spreaded around.

The community project Firebird 2.5 is released. You can read the press release and most importantly release notes. And sure, you can download it and use/test/deploy.

Please join Philippe Makowski, President of Firebird Foundation, and Dmitry Yemanov, lead Firebird developer, at the Launch Webinar devoted to the 5th major release of Firebird. It will take place at October 4, 2010, at 13-00 GMT.

Firebird is trully *open* (in all aspects). Nobody owns Firebird, nobody can buy it, nobody can close its sources, nobody can charge for it! So, if you are using Firebird, you don’t need to have such worries.

The second issue of Firebird SQL Project newsletter was delivered to all subscribers. This issue includes announcements of official Firebird channels at YouTube and SlideShare, the full list of materials from Firebird Conference 2011, and also digest of recent community news.
You can read the second issue online.

Now, this could be a very good opportunity for all of the other open source database servers particularly the most popular ones like Firebird and PostgreSQL. I’m particularly fond of Firebird (the InterBase offspring) and use it in many projects and did a lot of consulting to Delphi developers using it. Can this be the rise of Firebird?

I wrote the modification/tips needed for running RoR on Firebird

Migrations don’t work yet with RoR and Firebird but you can use Flamerobin for creating tables by hand