We have completed the MeeGo platform, so you can use that right now. It won't be 'replaced' with Tizen, and will exist alongside it. If the open source community for MeeGo OS decide to stop adding new versions, then we'll complete the platform with the latest stable version. Tizen is pretty new and there is no SDK we can check out at the moment. We are expecting something close to V1 in Feb 2012, so there is time yet. We are planning to work on HTML5 before then however, so the addition of the Tizen platform is something we should be too troubled by. As usual we will prioritise platforms based on how easy it is to add to our existing line-up, and the potential new users it will add to the AppGameKit ecosystem.
I drink tea, and in my spare time I write software.