I had a chance to compare the Pantone color on both iPhone screen and the "fan" strip. Pre-press and color-correction is my profession. So I think a software like this can't be a strict reference due to the different nature of color systems which emit light to those reflecting it. But it is a wonderful opportunity to the color communication, e.g. a designer could show a sample of color to his customer right away on the phone screen. Another problem with this app is iPhone's screen: the color depends a lot from the viewing angle. This is crucial to tiny hue differences between Pantone color items. Depending from the view angle a color can look like any of its four neighbours on the strip. BTW I didn't had a chance yet to investigate N900's screen from this point of view. I'll try to make a test and post it later. But at a glance N900's screen doesn't seem to have such angled hue shift as iPhone does.

But, I do like to have an app like this on my N900 as well.
I even tried to figure out how a device like N900 can be calibrated. Especially with its 16 bit color table.
Well, programming is not my good point. But as color enthusiast I'm ready to take part in this job.