So if you're in that world, now the attack vector is to get you to download something to your phone which can then use the tunnel to look at other stuff in your cloud. This isn't a whole lot different than now, phishing out your gmail password for example or keylogging it. VPN key stealing might be made more complicated by an authenticator type device (that may be too complex for Grandma though)
On the platform itself the OS isn't exposed. Not fun for computer people but better for Grandma. Jails/containers what not for apps which keep execution domains isolated, and resource consumption managed, Etc.
But to your point it isn't an "easy" solution to the problem of the ephemeralness of the cloud :-) but it does keep your access to stuff around. When I look at things like blu-ray players which run the script code in Blu-ray disks I think about virtual machines as containers might be an option here. Also running win98 in a vmware player. It is entirely concievable that some sort of environment is always virtualized for "long lived" compatibility.
Of course if I had all the answers I'd be hiring to build it rather than just making notes in my notebook :-)
That makes your "cloud" into something more like an encrypted storage container than what we currently think of as a "cloud." How would something like, say, Flickr work on that? How would other people see the pictures you share?
When Picasa loses favor with Larry and gets shut down, his data is still safe he has just lost his ability to point people at Picasa and can switch to Flickr. My assertion (which I agree is yet unproven) is that we didn't start designing things this way because bandwidth to the cloud was always better than bandwidth to your 'home' (which was largely dial-up early on).
But unlike a pure storage container I'd love to be able to use an email service which will 'drop off' my email into this infrastructure, which I can read at my leisure but not have it stored in the 'cloud' where it can get lost (or perhaps spied upon).
In some ways your satellite TV receiver (especially if it has 'sling box' type capabilities) is sort of along the system design models of having a captive bit of compute/storage in your home that offers you service on the road and at home, and the vendor can push content into. Think about that for services other than just TV.
http://en.wikipedia.org/wiki/Freenet#Distributed_storage_and...
You can guard against some of this on a personal cloud by having VPNs as a standard part of the appliance, but I suspect there are other problems that aren't as easily predicted or fixed. For instance, if my personal copy of Google Docs is running on my specific unit, how does it handle a DDoS? That's one big advantage of having a third party hosting and managing the servers instead of say, my grandma.