The cliff notes version? These apps are a great jumping-off point, but just remember you are looking at two completely different types of color- additive (light source) and subtractive (pigment). There are so many factors that get in between you and the recording of your perfect color. Like any other camera/compute screen, color calibration, color cast, light source, and many other factors will influence what you see. Color is all about context, so if the white point on your iPhone monitor is leaning more towards a warm tone or a cool tone, your color will not be accurate.
Designhole recently wrote a great review of Benjamin Moore and Sherwin Williams color-matching applications, both free for downloading. She astutely summarizes, "No color app is going to identify a color correctly when the camera is the problem. How could both companies fail to see this? At least they’re free."BM Color Capture
For another take, you can read this color app analysis.
Anyone have either of these nifty applications? What do you think of what paint companies are trying to do? Do you think it's successful? Let's discuss!
(Added 7-6-09: be sure to read the comments from this blog post, as there was a fabulous discussion that ensued. Great nitty gritty details about subtractive versus additive color mixing)