I was thinking the same thing. I see this as a massive misappropriation of tax payers' funds. I don't know what the accountants would say on the issue, but I'd imagine that isolation has a higher cost to the tax payer than general population since the convict needs everything brought to them in special quarters built to what I can only assume is a higher standard.
A simple firewall with some sort of websense technology should be more than satisfactory to limit the use of these networks by the inmates. I'm sure it's an issue of "If you build a bigger mouse trap, I'll build a bigger mouse", but there is definitely a finite number of social networking sites out there and I'm pretty sure that there's a room full of near-slaves working in a sweatshop somewhere in the East which are constantly updating those web sense filters.
Here's an even better idea, why not actually track HTTP POST requests to unknown sites as well. This way, when the inmate clicks a button to post something and the websense filter doesn't know how to handle that request, an administrator somewhere on duty will immediately see their screen and then click whether it should be allowed or not. This will allow the inmates to apply to online universities to assist in their rehab while mindless blocking known "Red Zones" like Facebook. I can't imagine that we'd need more than one person on duty for an entire prison corporation during one shift per day.
If the inmate can't post data, push a popup to the user saying "You're attempting to post information to an unknown or unapproved site." followed by "Please wait for approval by an administrator" or "The administrator is not on duty today. Please try your request another day".
This type of a system IS NOT hard to implement. It would be MUCH less expensive than keeping inmates in solitary as well.
I'm pretty sure the biggest problem with American prisons has to be that they are penal facilities instead of rehabilitation facilities. I'm pretty convinced there are such things as people so broken they can't be fixed, but I'm also pretty sure that goal of a prison shouldn't be to punish someone for 25 to life but instead should be to actually fix the problems. The people who seem the most hellbent on hate and punishment of these people often seem a lot scarier than the criminals themselves.
I always sympathize with victims of heinous crimes, but we the people become victims of those who choose to force us to pay for the punishments. When you get someone truly nasty and broken, I don't see we have a choice but to jail them for life. I'd prefer to see them locked in proper facilities to deal with their illnesses instead of exposing criminals of a less extent to them. I don't have an overwhelming need to pamper people who did crimes during their correctional stints. I do however HATE the idea of hardening everyone who enters the system so that some kid who got busted smoking a joint ends up in and out of prison for the next 50 years. If for no other reason than that I don't want to make even more damn hardened criminals, we need to make it possible for prisoners to be online, learn trades, self-discipline, responsibility, etc... but make no mistake, they showed enough poor judgement to end up there, they don't need access to entertainment websites. It should be a tool, not a toy for them.