Yeah, right now, because the card is basically just data from a database (and some of that info is actually not even from our servers - i.e. the image from Flickr) and a CSS stylesheet, printing direct from the browser uses practically no resources from the server.
The folks programming the site (our university's Office of Learning Technology), tell me that with the easy pdf fix, you essentially embed all of that info into a styled pdf file (create the pdf file but not just the one representing the normal "print preview" -an actual formatted version), host it momentarily on the server and allow the user to download from that temp pdf file. In all the pdf creation step and the actual pdf downloading step do require work from the server. They said it isn't like hosting video which can be very resource intensive, but if we expect a LOT of users it may just be enough to require some significant server infrastructure (i.e. $$) down the road.
My lab currently has two reasonably powerful servers (we also host scq.ubc.ca, terry.ubc.ca, and bioteach.ubc.ca - in all they attract about 20,000 visitors a day and are currently only using about 0.2% of our server's resources), and initial estimates suggest that we're "probably" o.k. with the pdf route but there is still the possibility for issues. For the site to freeze on us when the interest is high would be a big loss.
As well, we're also trying to develop a system that has potential use outside our site (i.e. the wordpress template will be made available for anyone to use and tweak). The reasoning was that if we allowed the pdf version from the beginning, it may limit the usefulness of the template for people using it without access or funds to host under these relatively intensive circumstances.
Anyway, this kind of discussion is really great, since it sets the stage for an additional community to get involved in the project (the open source, progamming community). And I think we'll still have a go in that when sets are initially offered, we'll have special multipage pdf files that people can download (kind of like it's ready to go), and monitor the load from there.
The programmers did seem to suggest that doing the pdf route and coming up with something that addresses the bandwidth load is probably doable, but that it could be something tackled later or (perhaps other folks can have a shot). I think once the wordpress template is released, I'll basically release it on this forum so that threads with the programming angle can be encouraged.