Maybe it's the finish that's yellowing, not the maple.

Some people will say that when the wood ages it changes color. I guess this is true to a point. I personally do not really subscribe to this theory.
More than likely what your seeing is the clear finish that was applied to your cabinets is turning yellow and perhaps even orange.
Now let me preface this by saying all to often kitchen cabinets are finished with what's called a "toned finish". This is a short cut that ALOT of cabinet companies use. This is when the color is mixed with the lacquer and sprayed on . It saves them a step in the process and allows them to put out more cabinets quicker. It also gives a more opaque look to the cabinets and allows the cabinets company to hide flaws in the cabinets.
Other factors would be if your cabinets are in direct sunlight for a good part of the day, as well what kind of finish product they used.
Are these new construction cabinets ?

Hmmmm, I guess I wasn't clear - these cabinets are brand new, installed about a month ago. I know cherry will darken over time, and my father's unfinished pine interior of his cabin has darkened over time as well as developed a sheen. My birch chairs have mellowed and are no longer as "clear" as they were 2 years ago. I wondered how maple looks 5, 10, 15 years later. Does this make sense, or am I totally off track?