Most of these reasons involve consumer-friendly features.
The New Features
Linus Torvalds (founder of Linux if you've been living under a rock) stated that the kernel has entered a "new world order" with 2.6.30.
Many of the reasons for this statement live in the PCI subsystem. For example, thanks to Alex Chiang, Linux now offers "real hotplug support." Also, the architecture for system hibernation was reworked to improve both suspend and resume.
There were also boot speed improvements along with hundreds of driver changes, the list goes on with far more than you'd want us to cover here. Those who do want to read the dirty details should check out the full list as provided by KernelNewbies.org.
Why Get Excited?
Every time the Linux kernel makes advances in ways that end user consumers can tangibly benefit, their chances of adopting Linux in particular increase. Since Linux is in some ways the poster child for open source, its improved standing in the eyes of the public benefits the entire open source community.
The phrase "a rising tide lifts all boats" doesn't just apply to an economy. One of the sticks proprietary vendors still hit open source with, with varying levels of success, is the claim that open source is just not user friendly.
Each stride made by major open source projects toward improving this situation lifts us all, even those who do open source on other platforms. So grab a raft and and hold on for the ride.