I think server-class ARM is interesting, but it's always struck me as much more interesting for on-premises stuff... like, you want a cheap on-site NAS that doesn't use much power, or a generic machine you can use as a switch, or maybe even an intranet host or something. Anything in the category of stuff that is always on but not very resource-intensive.
In cloud deployments, though, sharing a bigger box amongst lots of virtual machines just seems way more economical.
I kept a close eye on the ARM server market for years waiting for it to happen and bring cheap multi core boxes to the masses. Ultimately, I stopped caring when quad core Xeon boxes got down to less than $400 and draw less than 30 watts idle: http://amzn.com/B00FE2G79C
I still think that 30 watts idle are way too much for at-home equipment. At German electricity prices we're still dealing with $75 a year just for electricity. What I want to see is a reasonably powerful machine that is <5 watts idle (for the board, CPU and RAM) plus the power of the installed hard disks.
I think that where ARM could have a lot to offer is in distributing storage and compute more evenly... for distributed bigtable or cassandra-like storage, it could make a lot of sense to pair 16-32gb of fast ssd storage to a 4-8 core ARM node... With the amount of I/O bound data per compute node reduced, and lower cost per node, this could yeild much better results than the big boxes for distributed databases.
For many other chores, I'm not sure if it makes as much sense... but that's juse my $.02 on the issue. I still think it's a pretty cool option, but not sure how well it works for a lot of different areas.
It's interesting. I agree with you, and what I think about when I read your comment is that ARM serves best the role of decentralized computing in general (things like what you mentioned and a whole lot more), which brings up a bigger question: is there a larger role for decentralized computing in the future than there is centralized computing (server farms, cloud, etc.)? My guess is yes, and I'm not just talking about the "Internet of things", etc. With lambda architecture and data pipelining there is a good chance that these sorts of advancements (the advent of cheap ARM servers, etc.) and other changes in the ecosystem will mean a lot.
In cloud deployments, though, sharing a bigger box amongst lots of virtual machines just seems way more economical.