Actually, there can be a significant difference in beer taste in cans vs bottles vs kegs. It all depends on the brewery, specifically on their pasteurization process. The two most common beer pasteurizing techniques are flash pasteurizing and tunnel pasteurizing. In the flash method, beer is quickly brought to a high temp, held for set amount of time, and then dropped back down to a cold temp before being packaged in bottles, cans or kegs. With this method, all the beer is going to fast the same, regardless of it's packaging. In the Tunnel method, beer is packaged first, and then run through a tunnel where it is sprayed with hot water until the center of the package reaches a set temperature. In this method, the material used in the packaging, and the shape of the bottle/can/keg does in fact, have a significant impact on how long the beer must be heated for the center to reach the needed temperature, which can change the flavor of the beer. Both of these processes are ultimately designed to make beer more "shelf-stable", so that it can be shipped and stored at room temperature. In the US, domestically brewed keg beer is almost always unpastuerized, utilizing refrigerated trucks and warehouses to keep the kegs at a cold temperature from brewery to tap. Because it doesn't go through this extra "cooking" step, it WILL taste different than the same recipe in a can or bottle.