I'm going to be honest here, I just recently found this desktop publishing software.  It snuck up on me.  I've been using it over the last month on things and I've been realy happy with it.  This is an area I didn't think I would ever leave the main stream software and move over.  I haven't removed my main stream software yet, however at 5 weeks and not having to switch back to it, Scribus is looking more and more promising.

Scribus does the job as well as main stream software.  It does it for the wonderful price of $FREE! Yeah I like my $FREE software, but only if it does the job, if it doesn't them I scrap it and go with main stream software. 

Scribus is recieving active development and support from the open source community.  It's reaching feature parity, and if I was a main stream desktop publiching developer, I would be getting a bit nervous.