Marissa Mayer, a Silicon Valley veteran who was previously the head of local, maps and location services at Google, has been hired by Yahoo! to come in as their new CEO, their third in ten months and fifth in three years.
Mayer is one of Google's superstars. As the company's 20th employee, she is responsible for much of the backbone of the company, from the iconic simple white homepage (the original  was never as good looking) to some of the its strongest products, such as GMail, Google Images and Google News. She was also Google's first female engineer, and has consistently been one of the most important players.
But Mayer also hit a ceiling at Google. The "triumvirate" of co-founders Larry Page and Sergey Brin and the company's longest-running CEO, Eric Schmidt, was impossible to break into, leaving her one tier down. She still ran a very important department, and was on the company's operating committee, but there was little to no chance of her moving to one of the top jobs. Even though it comes as a surprise, then, her departure makes sense.
From Yahoo!'s point of view, choosing Mayer is very important for one key choice the company has to make: whether to turn towards media, or remain a tech company. Like AOL, another internet services company which leveraged its "portal" into a powerful content provision network, Yahoo! is a valuable media company in its own right, and many had assumed that its new CEO would come from that realm. But the inference one can draw from the hiring of Mayer is that Yahoo! views itself as a tech company first and foremost, and is trying to get that house in order before it goes anywhere further.
Neither arm of the company has been particularly well run for the past few years, and Mayer has her work cut out for her. PaidContent reports  the board's belief that "most of the company is search and mail and the home page," core competencies which Mayer will be familiar with, but which are also undoubtedly withering under Yahoo! as it is currently constituted.
And when it comes to more forward-looking services, Yahoo! has a poor history indeed. The company has previously acquired and killed – or as good as killed – the popular companies Flickr and Del.icio.us, earning it a twin reputation of being dangerous to be bought by and not the sort of place you want to keep your data. Mayer will have to work hard to overcome that reputation, and if the company can't buy its way out of the trouble, it will have to innovate instead, particularly when it comes to the mobile sector, where it has barely any presence at all.
Mayer has a peculiar set of incentives going into her new role. Having started at Google long before the company was profitable, she spent a lot of time being paid in equity: equity which is now extremely valuable. As a result, she is probably one of the few CEOs of a Fortune 500 company for whom her actual remuneration doesn't really count for much. Whether this is a good thing, allowing her to focus on the long term without worrying about the source of her next paycheck, or a bad thing, enabling her to take the sort of risks that no one ever would if they had "skin in the game", remains to be seen.
She is also a example of a woman determined to, in the words of a current debate , "have it all": Mayer is expecting a son in early October. The Yahoo! board didn't know that when they first approached her, but were reportedly unconcerned when they found out last Wednesday. Mayer, for her part, doesn't expect it to conflict with her new role. She told Fortune :
I like to stay in the rhythm of things. My maternity leave will be a few weeks long and I'll work throughout it.