1 million in 28 days equals about 35700 units per day.The 3G Version was only just released on friday. Taking into account that Apple is only serving the US market at the time that´s quite a lot. 

I´m curious about the figures when the iPad goes on sale in most of europe later this month.

According to what Gizmodo cites as reliable sources Apple´s german branch received orders for 250,000 iPads. The international launch of Apple’s tablet device was announced to be late April. Rumours predicting April 24th have surfaced earlier today from a Canadian website.