I have been keeping an eye on an articulation test for the iPhone/iPad called the Sunny Articulation Test. I wasn't willing to buy it at the usual price of $49.99, but today (10/9/2011) it is on sale for $21.99.
It is a qualitative test, not a normative test, so it will not tell you how your child/student/client compares to other children his/her age. However, it will test all phonemes in multiple positions of words. It allows you to easily record productions of each test item so that you can go back later and listen again. It has a screening mode and a full test mode. The screening mode has fewer words and you simply indicate right or wrong for each target phoneme. The full test mode has more words and you enter the type of error for each incorrect phoneme. The test automatically calculates errors and does some simple analyses (how many voiced sounds were incorrect, how many voiceless sounds were incorrect, how many plosives, etc.). You can also automatically generate and email a simple report.
I will do a more complete review once I have had an opportunity to actually use the program, but I wanted to let you know about the sale in case you've been looking for an articulation test for the iPhone/iPad.