Is Beer Can Chicken safe?
My main concern (would have been) BPA, as most cans nowadays are coated with BPA plastics inside to protect flavor.  Cooks Illustrated evaluated the BPA leeched into chicken using this method:


  Beer can interiors are coated with an epoxy that contains Bisphenol A
  (BPA). Is the popular method of cooking a chicken perched on an open
  beer can really a good idea?
  
  Some studies have linked BPA to cancer and other harmful health
  effects. To evaluate the ramifications of cooking chicken on a beer
  can, we roasted two whole birds, one set on an open beer can
  containing 6 ounces of beer and the other on a stainless-steel
  vertical roaster with the same amount of beer poured into the
  reservoir. After roasting the chickens, we collected their drippings
  and stripped each carcass, grinding the meat and skin to create
  homogeneous samples. We sent the samples to a lab to be evaluated for
  BPA content.
  
  In each chicken, the BPA measured less than 20 micrograms per
  kilogram, leading us to believe that the beer can cooking method is
  safe. (The Food and Drug Administration’s current standard for
  exposure is 50 micrograms per kilogram of body weight for adults, or
  3,400 micrograms per day for a 150-pound person.) For those who have
  any remaining concerns, there is always the vertical roaster, which
  works just as well as a low-tech option.
  
  Published May 1, 2011. From Cook's Illustrated.


There are several available vertical roasters that act just like a beer can.  Here's a photo of the Steven Raichlen SR8016: