Ethernet enabled multiuser device

Hey guys I am sure something like this has come up before but after searching for a few hours I feel like I have confused myself even more :0. Essentially the scenario that I am thinking of goes something like this:

John, Bob, Billy, Zach all connect their Ethernet enabled Arduino's on different networks at their respective houses. Then they all log onto the same website that is hosted on a remote Webserver (ie.. www.thesite.com). The site would have a buttons that could control the other peoples Arduino's (turn off and on pins). Is this possible? Are there any drawbacks? Any other ways to achieve this? Or will it have to be a coding nightmare as I am afraid of?

Thanks alot I just can't find a straight answer anywhere. I am pretty sure I should look into WebClient examples on the Arduino but everything I find is all local hosts not remote. Thanks again!

This is possible and lot's of applications work almost like that. The WebClient example is doing most of the stuff already. Local or remote hosts is not really a difference (from an Arduino point of view). If you have solved your project for a local host and one user, you have the solution on the Arduino. The rest is just the development of a multiuser application on the web server with all the complications like security (access permissions), concurrency, user management and device identification.

Thanks alot I just can't find a straight answer anywhere. I am pretty sure I should look into WebClient examples on the Arduino but everything I find is all local hosts not remote.

The arduino can run combined server and client code which might suffice for the individual houses. In your setup "thesite" would also have to handle both client and server actions, which is usually not a web site function. When a complex web page is downloaded by a browser, it generally appears that the browser is just interacting with the main web page site. In reality the browser is usually connecting with numerous other web servers via embeded links in the web page. In your setup, "thesite" may serve the control web page, but the page will probably need to include the links that allow arduino to arduino communication between the individual houses.