Is it possible to run Windows 8 apps in Ubuntu?

I read that new apps in Windows 8 will mainly be developed in HTML5 and Java-script. Those two languages are already supported in Ubuntu.

Hence, is it − or will it be − possible to run those apps in Ubuntu? How do I do that? Could you give me a practical example?

Or will it just be easier for developers to port their application to our platform? So will I have to wait for them to do the job?

This is not exactly accurate. Only Metro apps may be written using HTML5/Javascript/CSS in Windows 8. Microsoft is presenting HTML5/Javascript/CSS as one of at least two supported technologies developers may base their Metro apps on. (another is C#-based apps). In both cases Metro apps will run sandboxed in a special environment and will make use of WinRT which is a proprietary set of APIs and the accompanying platform support framework that will be included with Windows 8.

You may always try to run 'classic' Windows applications using Wine, but at least initially, you should not expect any support for running Metro style apps in Ubuntu. Besides, most of these apps will be closer to widgets rather than full-fledged apps and there are several widget solutions for linux.