Be constructive: you may point out issues in specific implementations in an objective way, but the goal is to improve interoperability, not to start flame wars.
Be open: every implementation contains bugs. If you happen to find issues during the testing, please note down a short summary of it on the wiki. Afterwards you can mark it as fixed, showing your commitment to interoperability and the real progress you've made.
Be focused: the goal of this wiki is to improve interoperability. Of course, you are free to add a link to your website and a short description of your implementation, but this isn't the place to announce new releases or write reviews.