So that shiny new 3rd Generation iPad that you picked up a mere six months ago, has been rendered obsolescent overnight by the untimely introduction of the new 4th generation iPad?
Except it hasn't.
Your 3rd generation iPad works just as well today as it did yesterday. Just because there's a new iPad doesn't mean you have to upgrade.
I have to say, I was one of the ones who were shocked by the unexpected introduction of the new iPad, but it's not a must have upgrade.
Yes, the front facing camera have been upgraded and there's a significant performance bump with the new processor. New connectivity and perhaps the most significant change for the UK is expansion of LTE support. But even with these new features, it's certainly not a no-brainer upgrade or even required. If you can afford it, go ahead, but really, your iPad 3 will give you sterling service for some time to come - probably until the next major upgrade to the iPad - the 5th generation.
We most likely won't see this now for another 12 months, so Apple might have done you a favour by not bringing out radically new machine in March ;-)
The iPad 4th generation is aimed at new customers and perhaps may give a push to those people on the fence about upgrading from the 1st gen iPad or iPad 2. It's really not targeted at 3rd generation iPad users.
So yes, it's always good to have the latest and greatest, but you don't need to fret about upgrading to the 4th generation iPad, there's plenty of life left in the old new iPad.