I stumbled upon Peter Hutterer’s “thoughts on Linux multitouch” which gives a good overview of the challenges facing X.org & al. in developing multitouch over Linux. Among other things he explains why, in spite of end-user expectations to the contrary shaped by competitive offerings, Linux multitouch is not yet available:

“Why is it taking us so long when there’s plenty of multitouch offerings out there already ? The simple answer is: we are not working on the same problem.

If we look at commercial products that provide multitouch, Apple’s iPhones and iPads are often the first ones that come to mind. These provide multitouch but in a very restrictive setting: one multi-touch aware application running in full-screen. Doing this is suprisingly easy from a technical point of view, all you need is a new API that you write all new applications against. It is of course still hard to make it a good API and design good user interfaces for the new applications, but that is not a purely technical problem anymore. Apple’s products also provide multitouch in a new setting, an evironment that’s closer to an appliance than a traditional desktop. They have a defined set of features, different form factors, and many of the user expectations we have on the traditional desktop do not exist. For example, hardly anyone expects Word or OpenOffice to run as-is on an iPhone.

The main problems we face with integrating multitouch support into the X server is the need for the traditional desktop. Multitouch must work across multiple windowed application windows, with some pointer emulation to be able to use legacy applications on a screen. I have yet to see a commercial solution that provides this, even the Microsoft Surface applications I’ve played with so far only emulate this within very restrictive settings”.

In summary, the reason why Linux multitouch lags behind some of its competitors is that it is a significantly more ambitious project with bigger challenges to overcome.

Among the links from that document, I particularly appreciated ‘s Bill Buxton’s “Multi-touch systems that I have known and loved” that provides a great deal of material to frame the debate over multitouch functionality – I feel less clueless about multitouch now…