Here is the survey data so far for the question on "Are you going to get the iPhone 3G?"
There were 449 responses which puts it at an accuracy of better than +/- 5%. Mind you this should be looked at not for the general public - but rather for those interested in the iPhone (YOU - why else would you be reading this).
But at least based on this data it looks like 50% of current iPhone owners are going to "upgrade" to the iPhone 3G. And of those currntly iPhone deprived - 64% will be getting the new iPhone (Mind you it is those iPhone deprived and interested in the iPhone - otherwise they would not have found this survey). Either way you slice it this means millions of new iPhone 3G customers very soon (talk about captain obvious).
Raw Survey DataDigg this