Indeed, when a huge international corporation like PepsiCo recognizes you in such a way that it prints its Twitter address on a Pepsi Raw can (only in the UK, but still), you can no longer be cool or rad; you're now part of the mainstream. Of course, those of us who are following Twitter closely know this already, but if anyone ever needs a defining moment in which Twitter went from being that little microblogging service to an online powerhouse, this is it.
The question that everyone's been asking at every such milestone - for example, when Oprah joined the service - is whether it means Twitter is making it big, or is it the start of its downfall? Actually, it's a little bit of both.
However, when you have a service whose goal is to become a basic utility, like water or electricity, this is exactly what you want: everyone, from regular users to major corporations, thinking of your service as one of their basic identifiers, similar to a phone number, email, or a web address. When other corporations, big or small, as well as politicians, musicians, actors and other public figures all start thinking of their Twitter account as an essential part of their online identity, Twitter has reached one of its most important goals. Jumping the shark might turn out to be the best thing that ever happened to them.