Phoenix Technologies' HyperSpace is also built on Linux and various other FOSS applications plus some proprietary code, but it is significantly different from Splashtop. It is installed to your hard drive, and it operates in two modes: hypervisor or standalone. Hypervisor mode, called "HyperSpace Hybrid", lets you run it side-by-side with Windows, and switch back and forth without rebooting. Hybrid mode requires an IntelVT CPU. "Dual Mode" is for systems without CPU support for virtualization, so to switch between HyperSpace and Windows you need to reboot.
Unlike Splashtop, you can purchase HyperSpace separately and install it on your PC. Hardware support is still limited, so check the specs first. HyperSpace comes with a Web browser, full multimedia support, wireless Ethernet and 3G support.
"How many times has your notebook crashed, making it useless? Wouldn't it be nice if you could still use your notebook even if Windows isn't working?...Continue safely surfing the Web, checking e-mail or watching that YouTube video even if a rogue application attacks and disables Windows. "
I would have said "when Windows isn't working" and "when a rogue application attacks." Still, it's a pretty big step to say anything like this in an industry that is chained so tightly to Redmond.
Phoenix estimates that most users can do 80% or more of their work in HyperSpace and don't need all the bells and whistles of Windows for the jobs they do the most often. Their goal is to make HyperSpace as reliable as a telephone: turn it on, everything works with no backtalk, turn it off or put it to sleep.
They claim up to 25% longer battery life with Windows in sleep mode (hybrid mode), and I suppose that in dual mode, with no Windows running, it should be equivalent to that or better.
The first thing I noticed was that HyperSpace takes about 30 seconds to come up from a cold boot, so it's not quite instant-on. However, sleep and wakeup worked flawlessly and instantly-- just close and open the lid. I did this for several days without shutting the power all the way off and it worked every time.