There are many technical benefits to beer in cans: no light, less oxygen leaking in, lighter and cheaper to ship, less breakable, and less damaging to foreheads. The beer heads have started to sing the praises of canned beers, but there still aren't too many craft beers available in them.
My initial thought regarding bottling versus canning was that canning would be more expensive for a small brewery. A recent article in the Houston Chronicle contradicts my theory and claims that canning lines are cheaper than bottling.
Canning lines are cheaper? As a home brewer, I've filled a lot of bottles. Bottling can be exhausting, but it doesn't require much of an investment to do it by hand.
Let's look at the can equivalent of crimping caps. Cask.com offers a manual canning system which has a nice video of a "manual" canning process.
To my untrained eyes, the "manual" canning process doesn't look much better than bottling by hand. In fact, it looks a lot worse, since those fancy can filling, seaming, and 6-pack ringing machines probably cost a bit more than my red plastic bottle cap crimper and leaky filling wand. At this level of automation, I don't think there is any way cans are cheaper than bottles. I'm going to declare bottles the winner.
At a larger scale the equipment becomes automated. Cask's automated system makes for a much more impressive canning video. It fills and seams at the impressive-to-me rate of 30 cans per minute. Unlike the manual canning line, chill background music is paired with the clanky machinery for the automated system. Nice upgrade!
Could this be cheaper than the equivalent bottling line? I'm not sure. This slightly higher capacity bottling line looks larger and more complicated. The canning line has a 1800 cans per hour rating. The bottling line is rated for 2000 bottles per hour, about 11% faster.
I'm not equipped to do a cost comparison for the more automated systems, but I think I can believe the canning line might be cheaper. Sorry, without getting quotes, I can't say for sure. I suspect that the biggest consideration for the craft brewer will probably be the marketing concerns of cans.
My suggestion for the marketing issues? Put your beer in big cans like Guinness or Young's, or in tiny cans like Red Bull. Another idea? Package the cans in cardboard carriers like bottles have. Hang a paper tag from the pull tab. Ship the cans in coozies or with a shoulder strap. Canned craft beer will need to do something a little unusual to pull attention away from the bottle section of the beer cooler.