A while ago, Máirín blogged about creating print originals in Inkscape and Scribus, and I can only chime in on her praise of these tools. Since I joined Imendio, a large amount of what I’ve done on a daily basis have been print work (stickers, t-shirts, rollups, tattoos etc.) and all of it have been done using a free software workflow!
A common obstacle you run into when using Scribus for print is the lack of support for predefined spot colors from Pantone, something that usually comes handy when you need more exact colors that you looked up in a color swatch. The reason that Scribus can’t include these is, as usual, because of legal reasons.
Luckily there exists a small howto in the Scribus Wiki how to get hold of and use these in your designs.