Beer produced by large breweries has long been sold in cans, but I've noticed recently that more craft beers are appearing sold in cans as well. Why might they be choosing cans over bottles? Is there a taste or shelf-life benefit to canned beer? Or is it just ecological or marketing concerns?
Cans have a lot of advantages over bottles: they don't allow light in (light spoils beer), are easier to stack (and take up less space when arranged tightly), the materials for each can are cheaper, and so on. From the consumer perspective, this results in cheaper and higher-quality beer, all else being equal.
The reason craft breweries have been using glass bottles rather than cans is largely historical and aesthetic. Some hip craft breweries started using cans recently, and it led to a trend.
Zach makes a good case for the benefits of cans over bottles...but there are just as many benefits of bottles over cans.
In general, I'd say that, if the beer is kept out of the light, bottles are a better choice as far as flavor is concerned.
For one, glass is completely nonreactive, and does not contaminate the beer, but aluminum does leech into the beer, even from lined cans. For an example of research on this topic, see this article.
Additionally, with lined cans, the plastic liner also contaminates the beverage; while, due to the small volume of plastic involved, this is likely less of a problem than in plastic bottles, it's still likely more of a problem than in glass bottles, where only the lid is lined with plastic, and (assuming the bottles are kept vertical at all times) the beverage has little contact with the plastic, reducing leeching.
With regard to longer-term storage, I've also heard pop bottle collectors say that cans eventually develop pinhole leaks, so the contents can't be kept in a can for decades, as they can be in a bottle.