What does rotating availability mean?

Rotating is kind of a hodge podge term. It might be seasonal, it might be something that gets released only every few years, etc.

 

I believe it'[s a term that the breweries use to tell you: "We'll brew this when we're damn good and ready."

 

The above definitions cover what a brewery might mean. I don't know if the OP was looking for the bar definition, but it usually means "whatever we can get but we don't know when we can get it, if it's available or if the distributor will sell it to us".

 

I'm taking you mean the BA availability descriptor. I've understood that as something that is released with regularity but does not fall into any seasonal listings. Examples would be things like Goose Island Bourbon County Coffee Stout (released each year but depends on production cycles) to things like Sam Adams Utopias which generally hits in the winter but not necessarily is produced each year.

 

Yes a rotating tap is "something from that brewery that the distributor can get for us" . It usually varies significantly over the year and I have found that for craft beer-centric bars in areas where the brewery in question has extensive offerings (more than say 3 beers available in the market) it usually isn't the major/mainstream year round releases of the brewery.

However at less beer-centric bars I've seen "rotating handle of brewery X" to include the major releases that are year round and do get widespread distribution but they vary as a function of time.

For example i can think of two places near me that have a rotating handle of Firestone Walker.
In one place a little less focused on beer it usually is DBA, Pale 31 or Union Jack all of which are on shelves all year around here.

At the other place which is a pretty hard core beer bar it has included Double Jack, Parabola, Abacus, The Anniversary Beers, Velvet Merlin....

 

For BA classification, this is something that is not produced according to a regular schedule, but is not retired. It could be produced every few months on an ad hoc basis when there is space available at the brewery, or it could be something that the brewery has not made in a year or more but intends to produce again, so is not retired.