I'm pretty sure there are Debian ports for ARM including RasberryPi.  
Here's an interesting project out of the UK 
http://www.southampton.ac.uk/~sjc/raspberrypi/ where the guy built a 64 
node cluster using Lego for the supports.

I'm also sure it was a lot of work like others have mentioned.

Perhaps when the upstream providers get the kernel and the drivers going 
in the Fedora and RedHat branches we'll see SL7 or 8 available for ARM also.

Joe

On 12/07/2012 11:27 AM, Konstantin Olchanski wrote:
> Please do not confuse 3 separate issues:
>
> 1) Linux userland: this is pretty much universal and will
>     run on any CPU as long as you have a cross-compiler
>     and as long as the "autoconf" tools do not try too hard
>     to prevent you from cross-compiling the stuff.
>
> 2) Linux kernel: is also pretty much universal and assumes
>     very little about the CPU. There *is* some assembly code
>     that needs to be ported when you move between CPUs (say
>     from hypothetical SuperARM to hypothetical HyperARM). I believe
>     current versions of Linux kernel have this support for
>     all existing ARM CPU variations.
>
> 3) Linux device drivers: in the PC world devices are standardized
>     around the PCI bus architecture (from the CPU, PCIe looks like PCI,
>     on purpose) and most devices drivers are universal, so if you
>     have a PCI/PCIe based ARM machine with PC-type peripherals ("South Bridge",
>     ethernet, video, etc), you are good to go. If you have an ARM machine
>     with strange devices (i.e. the RaspberryPI), you have to wait
>     for the manufacturer to release the specs, then you can write
>     the drivers, then you can run Linux. Rinse, repeat for the next
>     revision of the CPU ASIC (because they moved the registers around
>     or used a slightly different ethernet block). It helps if you have
>     some standardized interfaces, for example on the RaspberryPI you have
>     standard USB, so you can use "all supported" USB-Wifi adapters right away.
>
> 4) boot loader: is different for each type of machine, each type
>     of boot device media. period. (Even on PCs there is no longer any
>     standard standard - some use old-school BIOS booting, others use EFI boot,
>     some need BIOS/ACPI help, some do not).
>
> This makes it 4 issues, if you count the first (linux userland) non-issue.
>
>
> K.O.
>
>
> On Fri, Dec 07, 2012 at 01:01:36PM -0600, SLtryer wrote:
>> On 10/23/2012 12:37 PM, Konstantin Olchanski wrote:
>>> An "ARM platform" does not exist.
>>>
>>> Unlike the "PC platform" where "PC hardware" is highly standardized
>>> and almost any OS can run on almost any vendor hardware,
>>> the "ARM platform" is more like the early Linux days where instead
>>> of 3 video card makers there were 23 of them, all incompatible,
>>> all without Linux drivers. If you had the "wrong" video card,
>>> too bad, no soup for you.
>>>
>>> In the ARM world, there is a zoo of different ARM processors,
>>> all incompatible with each other (think as if each Android device
>>> had a random CPU - a 16-bit i8086, or a 32-bit i386, or a 64-bit i7 -
>>> the variation in capabilities is that high).
>>>
>>> Then each device contains random i/o chips connected in it's own
>>> special way - there is no PCI/PCIe bus where everything is standardized.
>>> There are several WiFi chips, several Bluetooth, USB, etc chips. Some
>>> have Linux drivers, some do not.
>>>
>>> As result, there is no generic Linux that will run on every ARM machine.
>> Not to be argumentative, but I always believed that the advantage of
>> *nix* was that it could be ported to numerous platforms, regardless
>> of hardware.  You even mention the "early Linux days," when there
>> was little or no standardization of PC hardware.  Yet, the platform
>> didn't disappear from use simply because there might have been
>> porting issues, most of which were caused more by proprietary
>> secrets and hardware defects than the ever-present fact of diversity
>> of hardware.
>>
>> But one could make the same argument even today:  That there are
>> many different CPU platforms, e.g., and that they are not
>> standardized.  One example I am thinking of is the Intel v. Amdahl
>> CPU compatibility issue.  Even though most of the Linux system will
>> run on either without modification, there are still some unique
>> issues to each of them; from having worked and studied VirtualBox,
>> there are differences in how each manufacturer chose to implement
>> the ring structure that permits virtualization to work as nicely as
>> it does on these platforms.  For the most part, they are compatible,
>> but the kernel developers have to be aware of certain implemention
>> issues, including a bug in the Intel CPU platform that requires a
>> VirtualBox workaround (for optimizing the code or something; I
>> forget).
>>
>> And this is in addition to Linux supporting umpteen different
>> processing platforms besides the x86 types.  New hardware appears
>> constantly, and some Linux user somewhere wants to use it on their
>> system.  I feel that variety of hardware and variation in hardware
>> implementation is a fact, and a main reason why Linux and Unix are
>> so powerful and ubiquitous.
>>
>> Now I just hope no one will hold me to this and insist that I
>> actually port Linux to all these different hardware configuration!
>> I'm not signing up; I'm just pointing out what I think is reality.