We've spent the last five months building a new Active Trainer. Active Trainer 2.0 is built with Ruby on Rails and uses EC2 and RDS from Amazon. When the beta was announced to the Facebook Couch to 5K fan page we received about 500 new users in the first day!
Anyone is welcome to join the beta. The only limitations currently is that there is only one training plan: Couch to 5K. But, you're welcome to make up your own workouts and schedule them whenever you like. Be sure to check out the "Feedback" tab on the left edge and let us know if you have any feature requests or find a bug. We've got big plans for this site in 2011 so stay tuned!