That rumour came from the same place as the retina screen in iPad 2 rumour, and it's just as false. There is no way Apple will move to a 6-month launch cycle on the iPad. There's just too much money in the annual upgraders, and they'll lose potential sales on the iPad 3 if they send out a signal that it will be obsolete in under a year.Rumor has it the iPad 3 could arrive as early as September, but even 11 months is a short time. You bought the iPad 2 for it's potential, which even you admit might not be fulfilled for months. You could've waited yourself to see if it was truly a worthy upgrade. The answer to your question is there isn't a lot, aside from a handful of games/apps (imovie, etc) which are iPad 2 exclusive, that 2 can do versus 1. If you facetime/skype videochat constantly, I guess you could use the cameras for that, but chances are you already have a device(s) that you use for that anyways.
I bought my iPad for £400, sold it for £300. That works out at less than £10 a month to use my iPad, which is a pretty great deal, and makes it very easy to justify an upgrade. Ditto with iPhones, Macbook pros. Never forget to factor in the resale value when buying it. In a year's time when the iPad 3 is out, my iPad 1 would have been worth very little.