The lead developer puts it bluntly on the front page at http://www.fireim.org/

We are saddened to announce that there will be no future versions of Fire. There are several reasons for this end, but the most notable is the loss of developers. Fire's development had dwindled to few developers who do not wish to continue the project alone. In addition, another major contributing factor is the fact that all but one of Fire's IM libraries is no longer in active development.