Apple CEO Tim Cook joined Twitter today as his company launched its latest iPhone 5S and 5C smartphones. His first tweet mentions his visits to the Apple Store earlier today as the new iPhones went on sale: "Seeing so many happy customers reminds us of why we do what we do."

While Cook's account isn't yet verified by Twitter, one of his first followers was Apple senior VP of marketing Phil Schiller, who also retweeted Cook's first tweet. Senior VP Eddy Cue also followed Cook just after the account went live. Apple's social media presence is fairly low (the company doesn't have an official Twitter account of its own, though there are accounts for the iTunes Store and the App Store), but Cook's move to Twitter coincides with the media tour he's been on as of late — it seems Apple is keen to put its executives in the spotlight during this iPhone launch. We've reached out to both Apple and Twitter to confirm that this new account is actually Apple's CEO.

Update: Cook's account has now been verified by Twitter.