Apple’s most recent acquisition of Quattro is a bit of a puzzler. While they can’t be discounted entirely, the only two explanations I have heard for it so far aren’t convincing.
Explanation #1: Apple is doing it to compete with Google (NY Times - "Aiming at Google, Apple Buys Quattro Wireless, an Ad Company")
Why not: Apple under Steve Jobs has not gotten to be the “company of the decade” by being reactionary.
While it makes sense to tap into advertising as an additional source of revenue, both to fund its own growth and to deprive its rival of income, it’s unlike Apple to enter a new product space as a me-too move. Apple has resisted building a competitor for Microsoft Office for some 20-odd years - iWork was developed because office software is an integral part of the average user’s computer experience, not to unseat MS Office. Apple needed to build it so Mac users would not have to suffer through an un-Mac-like experience with common computing tasks. They also sat out of the MP3 player market for years until they were able to leverage the integration between Apple hardware and software to drastically improve the user experience people had with MP3 players, and then did the same with the cell phone. For Apple, it’s all about the product.
Explanation #2: Apple is doing it to make more money from the iPhone platform (Business Insider - "Why Apple Bought Quattro Wireless And Is Getting Into Advertising")
Why not: Apple will make plenty of money from the iPhone already - they're not going to compromise the user experience just to make extra cash.
This article says that because free apps are downloaded 9 times more than paid apps, Apple "wants to think about ways it can make money off free apps". If that were the case, why not just make all free apps cost something? Sounds like a sure-fire solution to me. I don't know how much money Apple can expect to make off advertising, but considering it's usually fractions of a penny per impression, and many downloaded apps are rarely used, Apple could probably make more money charging less than 10 cents for each free app then they would by trying to monetize apps with advertising. Also, by promoting (or requiring) advertising in free apps, Apple would be actively undermining the user experience for their most downloaded apps. Sounds not at all like Apple to me.
To have a better guess at the answer, I think you have to assume that Apple is building a product where advertising is integral to what the product is delivering - meaning Apple is working on a product that could not achieve its required level of elegance without Apple having a direct hand in how advertising works on the device.
I can think of two industries where advertising is completely entrenched that would be appealing to Apple, and a third on the horizon that concerns Apple as well. The first is the magazine and newspaper publishing industry. The second is the network television industry. The third is the online application space, specifically online office software (Google Docs/Office 2010 Web Applications/etc).
Once the phone gets a little bigger, it becomes a good candidate to replace a magazine or newspaper, and when it gets bigger than that, it's a good candidate to replace your TV. The operating systems being developed for phones today stand a good chance of evolving into the next general purpose OS’s, leaving the computer as-we-know-it relegated to specialized tasks that require you to deal with the complexity of a desktop OS. A company that can stake a strong claim in the new methods of broadcasting and publishing that are being hashed out to reach the mobile marketplace has a good shot at the holy grail of living room media convergence that we've been hearing about for 10+ years: phone, TV, computer, gaming system, stereo, etc. Now THAT sounds like Apple, and that's the foothold Apple is fighting for here, not for the privilege of showing banner ads on a 480x320 screen.