I'm not normally a fan of Jean Baudrillard. His followers' emphasis on the "death of the real" has always irritated me, seeming more like a bourgeois justification of empty-headed pop cultural pursuits and trivial semiotics. But this Google Gmail business, I think, can be best understood in terms of Baudrillard's hyperreal: the real has been abolished behind an endless proliferation of signs, all pointing at one another -- the "real's hallucinatory resemblance to itself".
Look at it this way: The press release, itself an advertisement, is put out on April Fool's Day. Within this ad is the news that email will now be offered for "free", the only catch being the delivery of ads that are keyed to the email's content. The prospective customer is made an offer to trade her privacy for a gigabyte of storage and an email account.
Since April 1st is the traditional day when everything is taken as a simulacrum, everyone immediately assumes it's a joke -- ie., a put-on, a prank, a fake. Then the discourse takes a new line: Can we tell if it's really a joke or not? It seems that it really wasn't a joke, but that in itself is the joke: a press release too good to be true, which turns out to be true, released on April Fool's.
Google's press department has proved themselves masters of the Baudrillardian hyperreal. This is particularly apt use of reality-abolishing discourse, too, because it was an essential distraction from the nasty open secret of Gmail: that it will open your most private thoughts to the keyworded intervention of advertisers. The candy of a good joke makes the bitter pill of a new invasion of privacy easier to swallow, and the obvious objections disappear behind a dismissive "some privacy advocates say"...
The harsh, brutal reality is that a corporation will now be able to read your email, not just occasionally when a court intervenes, but as a matter of policy. But that reality is completely obscured by the play of this press release as a "joke" that turned out "true".
I think the joke's on us.