I think there has been a shift toward the plastic bottles and aluminium bottles in the last year or two, at least for the big name macro-brews.
CCL Inspiration 09
RCCL Explorer of the Seas Eastern 09
CCL Miracle Southern '08
RCCL Enchantment of the Seas Western '07
PCL Caribbean Princess Eastern '05
RCCL Explorer of the Seas Western '05
RCCL Explorer of the Seas Eastern '04
CCL Destiny Southern '01
CCL Sensation Eastern '94
CCL Ecstacy Western '92
CCL Jubilee Eastern '90
Around the pool it's either plastic or aluminum bottles... If you order an "import" (what is an import on a ship - everything is) that is in a real bottle it will be poured into a plastic cup. in other bars around the ship you can get real bottles and real glasses. In May on Triumph on Lido deck Bud, Coors, Miller were all in 16oz aluminum bottles. You could actually order a 12oz can of Coors Light.. you have to specifically request it.
we just came off the Miracle on Sept 29. They were offering it in 16 oz plastic bottles 4 for $18.00 a little over $20 with gratuity but by day 6 they were out of 16 oz and were selling 12 oz cans. We were on the Miracle last year and all they had was 12 oz and they were out of it last night of cruise. Some day they'll figure out they need more coors light out of the new york pier