Well i guess many of you might have checked the last edition of the Rails Magazine. If not, you may should.
In particular one of the articles by Rodrigo Rosenfeld Rosas talks about PDF generation with odf templates, something I’ve been playing around in the last few weeks. He explains the mechanism that can be used for this purpose and finally mentions the odf-report gem by Sandro Duarte which i’ve been using and forked to add support for image substitutions.
More info here: http://github.com/josecosta/odf-report
Give it a try!
UPDATE Fork was merged to master branch.