The last few weeks an interesting set of 3d designs appeared that have certainly got people thinking about the potential of modding and changing, mashing and merging elements together. It is the Universal Construcion Kit.
It does have an unusual acronym as the Free edition but all the pieces are there to download as open source designs
Being able to print just the right piece you need to mix Lego and Kinex is really intriguing. (not to self get soldering on the control board of your reprap !)
The great thing about the physical world is that it is starting to alter how people may see terms and conditions on software and other designs. Is this a breach of your Lego EULA to connect it to a competing plastic toy? Will the companies welcome this interoperability or seek to stop it through legal approaches? It has a correlation with what we see on other devices and software, that you must not modify or use in a way it has not been intended. However this clearly cannot be policed or enforced on kids toys as kids play with what they want in ways that suit them, not ways that suit the toy or toys.
So we could all learn a lot about modding and making from kids and be inspired by this particular development