New Scientist has an interview with psychologist/primatologist Tetsuro Matsuzawa (may require subscription for full article). He describes a number of ways in which chimps can outperform humans on cognitive tasks, especially certain tests of short-term memory. They're also better at recognizing upside-down faces, a skill that might be more helpful to a chimp (that spends time upside-down hanging from a tree) than to a human. He also states that ". . . wild chimps make use of about 200 plant species out of 600 in the forest. They can discriminate - they have a botanist's memory for these plants, their seasons, locations and their uses."
And, here's an interesting tidbit related to chimp color perception:
In many ways, chimps' perception and interpretation of the world is as developed as ours. For example, chimps recognise the same boundaries on the colour spectrum as humans. I can't say anything about their subjective experience of colour, just as I can't say anything about yours, but chimps trained to call the primary colours by their English labels attach those labels to the same parts of the visible spectrum that humans do.
Here's a link to a note I wrote at Stanford Law School on legal and ethical issues related to great apes, like chimpanzees.