These folks called Sensitive Object, along with Quividi, are a great example of French innovation.
The acoustic technology developed by them has a number of applications and it’s well worth a visit to their stand at next week’s Digital Signage Expo 2008 (like Panphonics’ Sound Shower it’s not something you can easily get to grips with unless you experience it).
Sensitive Object is a specialist in human-machine interfaces and designs and develops technologies based on the time reversal of acoustic waves (yes, exactly?)
Seriously their technology has a number of applications; Touch screens, POS, ATM, Kiosks, Shop Window Displays, Billboards as well as what they describe as ‘Anti-vandalism outdoor interfaces’
If you can’t make the show then take a look at their virtual showroom 
Sensitive Object is a French start-up company created in 2003. Its mission is to make any object or surface interactive by utilizing its ReverSysTM technology, based on the principle of the time reversal of sound waves in solid materials. The fundamental benefits of this process are its simplicity of implementation and speed of execution for an optimum efficiency.