I suppose it's worth mentioning in this thread what the British solution is to this self-inflicted problem, which is to pay the renewable energy suppliers (at least in the case of relatively big suppliers like windfarm operators) to turn off their supply. The total payments expected to be paid in 2011 (for not producing electricity) are £10 million according to this article:
Apparently these payments have been much more modest in previous years, for example just under £200K in 2010, but the payments have increased in size dramatically this year.
As I understand it, there has always been some inherent capability in the grid to handle some intermittency like a 1GW size power station suddenly becoming unavailable, and it may be that the amount of intermittent renewable energy has this year gone past the critical point of being able to take advantage of the existing back-up power arrangements.
The article attributes the substantial increase in payments to some sort of administrative change, so it could be Chis Huhne finding a way of giving his renewable energy supplier friends even more money, or it could be some strange tactic in the 'grid needs to be modernised to accommodate renewable energy' agenda.
According to the Times (via the GWPF site) the final figure for the amount of money paid out to UK wind farm operators for NOT producing electricity in 2011 was £25 million, quite a bit higher than the £10 million estimate I quoted in my previous post.