Are there any portable Windows 8 Store Applications available? I want to install and run it on multiple Windows 8 devices without an internet connection, using portable devices (for example, a USB Stick).
Windows 8 apps can be run on more than one version of windows, if you sign in with the same account that bought/installed them.
If you want to transfer apps to another PC without an internet connection you can use Windows Easy Transfer, you can choose to transfer just settings, just apps or both.
Windows 8 Store Apps apparently cannot be backed up or copied and side-loaded onto other PCs. So for IP reasons you will only be allowed to re-install by downloading the app again from the Store. For the same reason I don't see how portable Store Apps will be possible, since they would go against this principle.