When you look at the pain points Google plans to address with its ambitious Chrome OS, it’s hard not to get a sense of déjà vu. The search giant has said that its upcoming operating system, which will be available on netbooks by the second half of next year, will boast much faster boot times than today’s PCs, be less vulnerable to malware attacks, and generally cause fewer headaches than Windows. In other words, Google is ripping a page from Apple’s marketing playbook—and, if I were Apple, I would watch my back. Of course, the Chrome OS likely won’t look or feel like Mac OS X. This open-source platform, according to Google’s blog, will have a stripped-down user interface that “is minimal to stay out of your way.” In other words, don’t expect fancy Stacks or Cover Flow-like eye candy. Google is emphasizing the Web and robust applications that run inside the browser, whether you’re online or not. So what does Apple have to fear from little old Chrome? Just look at who Google has already signed up. In a follow-up blog post, the company confirmed that several heavy hitters will be working with Google to support its new OS. On the hardware side are Acer (the No. 1 netbook maker) and HP (the No. 1 notebook maker overall), plus ASUS, Lenovo, and Toshiba. The only big gun missing from that impressive roster—so far—is Dell. Other partners include Qualcomm, Texas Instruments, and Freescale, all of which are making ARM–based processors for next-generation smartbooks. Last, but not least, is Adobe, which pretty much tells you that the Chrome OS will fully support Flash come hell or high water, a feat that thus far has proved difficult on the more smart-phone–centric Android. When you look at Apple’s market share, which stands at 5 percent worldwide and about 10 percent in the U.S., it’s more than respectable, especially given the premium associated with Mac hardware. But Google Chrome OS will likely take a big bite of Apple once its partners hit the ground. Their devices will likely cost considerably less than anything in Apple’s lineup while delivering the “anti Windows” experience many consumers crave. Moreover, Chrome will likely be as customizable as Android, which will allow Acer, HP, and others to differentiate their wares with proprietary software—much more so than they can with Windows. At the same time, the new OS should allow consumers to personalize their Chrome experience in ways Mac cannot. To be sure, Chrome is an unproven commodity, and there’s much to be said for the tight integration of Macs’ hardware and software. Plus, the second half of 2010 is a long time—and several Apple product launches—away. Nevertheless, on day two Google’s OS already has more momentum behind it than all the other Linux upstarts combined. And now Apple is faced with the reality that in this next critical stage of the OS wars, merely “thinking different” than Microsoft won’t be enough. Editor-in-chief Mark Spoonauer directs LAPTOP’s online and print editorial content and has been covering mobile and wireless technology for over a decade. Each week Mark’s SpoonFed column provides his insights and analysis of the biggest mobile trends and news. You can also follow him on twitter.