A quick look at the old, blue label for Winter Lager, available as of last year, shows that there was nothing stating that it was a malt beverage.
So what is a malt beverage and how is it different than a malt liquor? Both malt beverages and liquors are fermented with malted barley, but malt liquors are usually higher in alcohol than a plain ol’ lager or ale. Malt beverages, however, may have as little as .5% alcohol. Malt liquors are often made with adjuncts—corn or rice, which, when fermented, yield higher alcohol contents. Malt beverages can contain all sorts of different ingredients, including natural- and artificial-flavors. Things like Smirnoff Ice and Coors Brewing Co. Zima are examples of malted beverages. They taste nothing like beer (and are often clear), but—and this is what is important—can be sold along side beers. They’re regulated the same way.
Why is Winter Lager now classified the same way as Zima? It’s alcohol content is 5.5%, which makes it high for a malt beverage, but way too low to be called a malt liquor, and Samuel Adams doesn’t use adjuncts. I believe there is some state that insists that Winter Lager is too dark to be classified as a lager (some states’ liquor regulations border on the obscenely stupid), but since it is brewed with a malted barley, it can qualify as a malt beverage, thus allowing it to be sold along side other lagers. Samuel Adams is pretty serious when it comes to classifying it’s beer, so I’m assuming this was no small thing.
Of course, I’m just a slightly tipsy fan who noticed something different about a label. There might be some other reason.