I can not find any documentation about Firebird being included in their software. The only place I could see it mentioned was that uninstall information.
I am a web developer and also maintain the Macs at our office. I try new things all the time so my machine can have all sorts of junk. But the photographer only use Mail, Safari and Photoshop. So when I saw that he also has the firebird user I tried to figure out the common denominator and that is the printer. So I think CWS is the root but I cant be 100% sure of course.
I could see two different behaviours when I cloned our Macs to new hardware. One computer said that I could ignore the firebird user and it was empty (no subfolders). The rest of the computers did not say this and they showed some sub folders under the firebird account.
I dont mind that Fiery use open source technology for their needs but this looks like a bug in their software and if so they should address this.
If you have contact with them over the phone please show them this page. It would be very interesting to know their take on this.
Images
http://dl.dropbox.com/u/231879/mac/migration.jpg
http://dl.dropbox.com/u/231879/mac/after_migration.jpg