One of the main reasons for the kind of exposure that Linux is getting is because of the vast amount of hardware it runs on. The Linux kernel has been ported to everything imaginable, from the tiniest computers to the largest space-ships and everything in between. The reason for this variety is due to the modular nature of the kernel, which suits everything it's tried on. These days, the talk of the town is netbooks. These tiny devices have taken the computing scene by storm and every manufacturer is running around trying to sell one of their own. And owing to the miniscule sizes and light workloads, the limited hardware on these netbooks requires something like Linux to fully appreciate the ability of the hardware without abusing it.
But long before netbooks came mobile phones. At one time, they were nothing more than a mobile telephone. But with increasing hardware/computing capacity in tiny sizes, more and more features came to be added into these devices. It's not uncommon for a phone today to have more processing power than a computer from 10 years ago. But while the processing speeds and capabilities have increased by huge margins, you still need a light operating system to make use of everything efficiently, owing to the limited battery life and variety in hardware specifications. And that's where Linux comes in.
Just like on the desktop, the distribution of Linux has been pretty fragmented in the mobile phone scene. You have consortiums, groups, operating systems and foundations by various groups, all of them going their own way towards an operating system or toolset for phones. Here are a few groups which are genuinely working towards getting Linux onto cell phones.
Originally a company that made software for mobile phones, Android was bought by Google in July 2005. As soon as the news reached everyone, rumors spread that Google was planning on entering the mobile market, but their intentions and plans were unknown. Finally, in September 2007, those rumors were confirmed when it was discovered that Google had applied for various patents related to mobile phones.
A beast the size of Google was always going to attract a lot of eyeballs. And now that it had decided to enter the mobile-phone market, lots of other companies wanted a piece of the pie, too. The result of this was the Open Handset Alliance, founded in November 2007. The alliance is made up of the following companies: Google, HTC, Intel, Motorola, Qualcomm, T-Mobile, Sprint Nextel, NVIDIA, Sony Ericsson, Vodafone, ARM, Asus, Toshiba, Garmin, and a few more.
The Android operating system was revealed to be an open-source distribution of Linux, which would be available on a variety of devices from various manufacturers like HTC, Samsung, Lenovo, Sony Ericsson, Acer and many more. Owing to the modularity of the kernel and its open-source nature, Android is expected to be ported to hundreds of devices with varied feature sets. For more info, check out the entry for Android on Wikipedia.