I thought this was going to be a joke, and that actually you buy a Sheeva and plug it in at home. I don't think you can yet buy connectivity so cheaply, but if you consider it as a fraction of your existing connection... + electricity cost per month.
Of course, there are advantages for managed, off-site servers. And I applaud http://pluggr.info for kicking it off. It may not be the ideal deal, but it may (who knows?) exactly suit some niche, well enough, that's big enough - and that is all that matters at this stage.
I think businesses would go more for not owning the Sheeva, and instead paying less, and also getting automatic "free upgrades" when the next performance level comes out (in the next 3 minutes.) That's a different organization of costs and finances for pluggr.info, which probably doesn't suit them (yet), but which I think would be more profitable both for them and for (business) customers. But if you got a niche, you got a niche, and you've gotta start somewhere! I hope these goes well for them.