Apple in the US has updated its online store today, adding a shipping date and pre-order buttons for the different versions of the iPad 3G. And it looks like Americans will be able to lay their hands on the the 3G variant of the device “by May 7th”. As with the Wi-Fi model, each customer is currently able to pre-order a maximum of just two iPads online.

Pricing: $629 for the 16GB iPad 3G, $729 for the 32GB model and $829 for the 64GB model (needless to say, these 3G iPads are Wi-Fi-enabled as well, which is why Apple calls them “iPad with Wi-Fi + 3G”).

Data plans: $14.99 for 250MB per month or $29.99 for unlimited data (with AT&T). Here‘s Apple’s new, dedicated iPad 3G page.