It's not promotional, it's the right way to report size. Operating systems report size in a wrong and confusing manner, except Snow Leopard.
Under the SI standard, storage is reported in base-10 (kilobyte = 1000 bytes, just like kilometer = 1000 meters). Under the IEC standard, storage is reported in base-2, with distinct names (kibibyte, abbreviated KiB, for 1024 bytes).
So most operating systems measure GiB, but display it with the GB suffix, which is of course confusing.
... But on the flipside, the "byte" is not a SI unit, and therefore legally the SI rules don't necessarily have to apply.
Even if the SI decided to adopt a unit of storage (which they haven't), it would almost certainly be the "octet" rather than the "byte", because the definition of a "byte" is technically obscured due to historic usage. (Is it 5 bits? 8 bits? 9 bits? Correct answer: Suprisingly enough, all of the above and more.)
Therefore, the definition of the GB is entirely up to the whims of the person publishing claims. It would be irresopnsible for anybody claiming to discuss storage capacity to fail to indicate clearly whether they're taliking about the base-1000 unit of the base-1024 unit.
But in the absence of any fine print to the contrary, it is entirely justifiable for anybody to assume that an unqualified "GB" is talking about the base-1024 unit.
Let's just agree that, depending on the circumstances, they may both be right. Right?
By the way, as far as operating systems go, Ubuntu is particularly confusing in its reporting, because some of its utilities correctly use the term "GiB", but others still use the term "GB" without disambiguating.
