Personally I'm upgrading to iPad 2 , my son has always got my iPad and I hardly get to use it , so I'm giving him and my daughter that to share.I'll then have the iPad 2 for myself, kid app free.if I find out later it's not worth having two iPads then I will just
eBay it.I'm not bothered about the cameras but the faster speed and graphics combined with it being thinner and bit lighter are well worth the upgrade for me.if there is a dramatic upgrade with iPad 3 that I just can't wait to have and I can afford it at the time, I will
eBay my iPad 2 and put the difference towards the new one, kids will keep the original iPad as it won't be worth as much as the iPad 2 by then.
This year I would have given the new iPhone 4 a miss as I'm happy with mine but I need a bigger capacity so that's swayed me,need to upgrade to 32g as I'm running out of space on mine for apps and it's annoying to have to erase them. I'll get the new one, hubby will get the iPhone 4 if he wants it and my daughter the 3GS (that my husband has now) and my son will get my daughters original iphone so everyone's happy.
Iv got it all worked out lol those are my reasons for upgrading and I'm sticking to them.
I would not however do this with a pc and usually get the best specs i can at the time and keep it for good 3 years before investing in a new one, then passing it on to the kids.