Apple did it again - they released a great product called the iPad. However, the main reasons that people buy these products, is that it is good quality and they do things better than the competitors. However, in order to protect the business model of Apple, and in order to ensure a good overall consumer experience, Apple restricts what applications can run on their devices. Google Voice was not initially accepted in the Apple app store, but Google has a great interest in making sure, that their services are universally available. Their solution was to create a Google Voice web application, that does the job, and now Google Voice is available on the iPhone.
Google Native Client expands the capabilities of the web, so that web applications can contain codecs, 3D graphics and code that requires a lot of computations, and still run well. HTML5 includes offline capabilities, and in combination, there is a complete framework for writing offline native apps delivered via the internet. The app store will no longer be needed by those that provide apps for free, unless they have very specific needs for access to local hardware.
Apple has a choice, but if they refuse Google NaCl, they will make their products to do less than the competing Android and Chrome OS products. Apple's products will be inferior. This will work as long as there are no significant apps for Google NaCl.
Google Chrome OS includes NaCl and is basically a lowest common denominator OS, where all the applications for it can also run on other OS'es. By providing Google Chrome for Mac+Windows+Linux, Google provides a platform that is large enough to make it interesting for app developers. It's standards-based, it's Open Source, it's easy and capable, it's free, it's cross-platform and it is huge. Apple can be in or out.
Apple is free to pick the default choices on their devices, and can limit access to local storage for web apps. But competition is catching up, quickly, and Apple needs to invent more. I would not be surprised to see Apple become very active in delivering a cohesive webservice offering similar to Google's. What's next, Apple buying Yahoo? Does Microsoft have anything to offer, or have they completely lost the consumer market?