Dog and pony act (or show) means a presentation, usually done by a corporation to bring attention to itself or one of its products.

I don't know the derivation of the phrase but I would guess it is from the circus world. In a three ring circus there is always the act that has the ponies parading in a circle going clockwise while there are little dogs jumping from horse to horse in a counter clockwise motion.

It can refer to any type of presentation or act but sometimes has a negative implication to mean that the presentation had no substance, just a shallow and cheap entertainment or cheap thrill.

"Slang: the Authoritative Topic-by-Topic Dictionary of American Lingos from all Walks of Life" by Paul Dickson (Pocket Books, New York, 1990 & 1998) has two entries.

(1) "dog and pony show: press conference; any carefully prepared performance."

(2) Pentagonese (the language of the Pentagon): "dog and pony show: Formal presentation aimed at gathering support for a system or issue. Visuals (usually projected on a screen), handouts, and large graphs are essential to a true dog and pony show."

When talking about a "dog and pony show," it's important to adopt a world-weary manner, as in:

"Oh, we have to put on a dog and pony show for the financiers."

Note that although this is very much an American phrase, it has also now entered British business conversations.    

Adapted from "The PhraseFinder"