If you preordered your iPad 3G before today, there is a slight chance that you will still get an end of April delivery. This was sent in by a tipster:
To Our Valued Apple Customer:
Thank you for your recent order of the magical and revolutionary iPad 3G.
We would like to confirm that your order will be shipped in late April as communicated at the time you placed your order. You will receive a confirmation notice when your order has shipped.
The iPad 3G will be available in store on May 7th and if you were hoping to get it sooner I hope you preordered it!