Update: The date turned out to be incorrect; Ranch is not available for download today.
The release date for Pokemon Ranch has been posted on a few gaming websites, such as IGN, as set for Monday, May 12th (tomorrow). However, no official press release from Nintendo has named the release date, nor has Pokemon.com. Be sure to check your Wii Shop Channel tomorrow to see if it is available for download and if the date is correct! If it is not, we will have to wait a little while longer for it to be released in America.
For those of you who do not know, Pokemon Ranch is basically a storage system on the Wii for your Pokemon. It allows you to interact with your Pokemon in a virtual environment and receive special Pokemon (like Mew). In Japan, it was released on March 25th.