New this build: experimental support for exporting to Windows Phone 8 and Firefox Marketplace (Open Web Apps)!
Note both these new exporters are experimental: the Windows Phone 8 exporter hasn't been tested beyond the emulator in Visual Studio 2012 because I don't have a real device to test it on, and the Open Web App exporter currently only works with Firefox Marketplace which is itself still in beta. Please let us know of any problems you encounter so we can investigate.
There isn't currently any documentation on how to export to either platform - as usual, we will make sure this is done in time for the next stable release. However until then, to publish to Windows Phone 8 note you'll need Visual Studio 2012 Express for Windows Phone 8. Firefox Marketplace is like Chrome Web Store hosted apps - you'll need your app uploaded to your own host. An important point is to make sure your server associates the .webapp extension with the MIME type application/x-web-app-manifest+json (and as with any site, also make sure .appcache is associated with text/cache-manifest for offline support to work). Then you can submit it to Firefox Marketplace. Note Open Web Apps can support other stores: part of the open philosophy is that it's possible other companies apart from Mozilla can start their own stores accepting Open Web Apps. So you might want to watch out for developments there as well.
There are also some improvements to CocoonJS integration detailed below - also experimental!
Finally, Steam recently confirmed that Construct 2 has been greenlit. Huge thanks for everyone who helped vote for us - hopefully we'll have more news to report on this soon!