It's some dumb marketing gimmick. The idea basically seems to boil down to "only old foggies use the major gTLDs these days, lets be hip and make our company name an adjective that is also our URL".
It's more than a gimmick. A recognizable and memorable URL has proven to be extremely beneficial to new startups. Memorable .com addresses are becoming endangered, or very very expensive.
To this day I have to doublecheck myself on where the '.'s are places in "del.icio.us" (in fact, it abandoning this URL some time ago). Now, "amazon.com"? Absolutely no worries there.
