If the original iPhone launch was anything to go by, it's unlikely we'll learn the answer to this poser for a while, but analysts and Apple watchers have been weighing in with their best guesses for how many iPhone 3Gs were sold on the device's debut this weekend just gone.

Although the second-gen launch was a much larger affair - with a same-day debut across 22 countries - this time round, because of stricter operator agreements, there were no online sales via the Apple store to boost numbers.

Fortune blog Apple 2.0 has rounded up a few of the estimates, starting with RBC Capital Market's Mike Abramsky, who said that worldwide sales for the first weekend would be more than one million units while the investors at The Mac Observer’s Apple Finance Board guesstimated 800,000 for the United States.

Oft-quoted analyst Gene Munster said he thought Apple and its partners sold about 390,000 iPhones worldwide on Friday and Saturday and 425,000 over the entire 3-day weekend with 225,000 of those US sales and 200,000 overseas.

Sales for the first day and a half of the original iPhone's US launch were 270,000 units. In January, after the phone had launched in the UK, Ireland, France and Germany it was revealed Apple had sold four million iPhones.