Originally, I estimated a price drop in the 8GB iPhone would come around September '08, along with the release of a 16GB model, in order to make that one push for Christmas in order to fulfill their stated goal of 10m units sold by the end of 2008.
I suppose the slightly-lower-than-expected sales in Europe pushed that forward, surprisingly to February, in order to keep the sales trends up. Interestingly, they didn't drop the price of the 8GB and introduce a 16GB at the old price point, instead they added a higher price point for the 16GB model.
This makes total business sense: give people the option that if they want more, they can pay more. Also, since apparently Flash Memory prices haven't come down sufficiently for them to shift the price points, introducing the 16GB model at a higher price is simply the economy to-scale.
I wouldn't expect a price drop in the 8GB model until September, when the market has matched the value of the Flash Memory, or they introduce a new model.
With regards to the new (possibly 3G model), it's obvious that Apple are going to have to go through the same FCC application process as before, and will want to announce the unit 6 months before it ships. The obvious time to do this would be MacWorld 2009, with a ship date of June 2009. Since once the iPhone 2.0 model is announced, they can expect a sharp drop off in sales (as people hold off their purchases for the new model), that would be the time to be "giving iPhones away", in terms of really cheap prices, and adding a slew of new features to make them as attractive as possible and make that decision to "hold off" as difficult as possible
While we're on the topic, let me just go ahead and put my 2¢ in that other than 3G, it's likely that the iPhone 2.0 will focus more on photography (ie. a 3MP or 5MP camera) with tighter integration with iPhoto. After all, there's only so much you can do with music & videos... That is, assuming that Calendar/ToDo/Notes & iChat functionality are rolled out on the current iPhone (Apple FTW!)