Ever since Steve Jobs made the decision to switch to Intel Microprocessors in 2006, he has spawned a community of hackers that install OSX onto non-Apple computers. Since current Apple computers are in fact just glorified PC's in a sleek designer case, albeit with a superior operating system, the possibility of hacking and creating your own home brewed version is now greater that ever. Combine this with the popularity of sub $600 netbook's from manufacturers such as Dell, MSI, ASUS, Acer, and Samsung, then you have created the perfect hacking storm.
The two most popular candidates for OSX conversion are the Dell Inspiron 9 Mini and the MSI Wind U-100. Both of these make a great "Hackintosh" with extreme portability and very little compromise in functionality, while at a much lower price point then the absurdly expensive MacBook Air.
You can find out more on how to "Roll Your Own" at message boards such as mydellmini.com, msiwind.net, and osx86project.org.
By the way, the photo above is of a rebadged Dell Mini 9 running OSX. Just don't tell Steve Jobs, he knows where I live.