I've received a few beer club shipments, and have received both cans and bottles. Personally, I prefer the bottled beer. I have no problem drinking right from the bottle (well, except for the 750's that I received from the Rare Beer Club), but if I pop open a can, I feel the need to pour it into a pint glass.
The Clubs of America Beer of the Month Club sends in their shipments “a 12 pack of four (4) different types of fresh microbrewed beer in 12 ounce bottles (and sometimes cans).”
The Craft Beer Club includes in their FAQ, “Why did my shipment include cans?” (answer: “up to 4 shipments out of a 12-month period we will include cans”)
As for the Microbrewed Beer of the Month Club, cans were first included in their March shipment, and members can expect cans again in September. Further regarding craft beer being canned versus bottled,
The recent surge in craft beer canning can be attributed to many different beneficial factors, including the lower packaging costs when compared to bottling and the increasing availability of mobile canning operations. In addition, cans offer excellent protection against the harmful effects of sunlight, can help keep beer fresh for longer periods of time, are lighter and safer than bottles, and are more environmentally friendly.
So much like synthetic corks (or screw caps) on the wine clubs that I've been receiving, expect to see more cans in your beer club shipments.