The latest iPad rumour to surface is that Apple may be about to launch an iPad with a haptic display at tonight's launch event in San Francisco. 

Haptic technology can be used to create a screen with 'textured feedback' by means of a small electrical stimulus. These pulses push back against the finger to create the sensation of physical touch. At it's most basic this can feel like a button push, but a detailed implementation can give the impression of textured display, enabling you to feel buttons, grooves, and surfaces displayed on the screen.

There has been limited implementation of haptic technology in some smartphones (such as the Samsung Anycall), which have given the impression of the screen buzzing when you touch it.  

However, Haptics can be implemented in a much more detailed manner by having an electrical pulse available behind every pixel on the screen, and at differing levels.

It is well known that Apple is investigating haptic technology, and the company has taken out several patents regarding haptic technology; but it is unknown when (or if) Apple will actually implement the technology.

The invitation for the iPad launch event on 7 March 2012, however, featured the words "We have something you really have to see. And touch". Apple uses cryptic messages in its invitations to hint at the 'big reveal' and some commentators have implied that the iPad will be available on launch day (so you'll be able to touch it), but some commentators have pointed out that haptics may part of the launch. The launch of the iPhone 4S, for example, featured the phrase "let's talk iPhone", which in retrospect refers to the implementation of Siri voice technology. 

Apple has also been believed to be talking to a Finnish startup called Senseg, that specialises in high performance haptic display technology called E-Sense. Journalists from The Guardian newspaper recently asked Petri Jekonen, Senseg's technical marketing manager, whether Apple was a customer for E-Sense, and he replied: "That would be for Apple to say. My comment is no comment."

The iPad is also expected to feature a higher definition 'retina' display and Siri, technology implemented in the iPhone 4S, it may also have an upgraded Apple processor with four-cores.

Macworld will be attending tonight's launch event, and we will be be running a live feed as the announcement is made. Check back here at 6pm to see what is revealed.