According to 1UP, retailers have been telling Sony to change the PSP, or else they'll stop carrying the machine altogether. Shipments of the system plummeted about 72 percent from the year before, with a meager 10,000 machines shipped to retailers last Fall. (Of course, the system has gained much more momentum at the beginning of this year. Looking at hardware sales, one can see that the PSP is still doing well--just not as well as the DS.)
Retailers have supposedly asked that Sony reduce the price of the PSP, but apparently, there's no plans for a price cut. At the Destination PlayStation event for retailers, Sony announced something else that got retailers excited: what it is is unclear at this point.
The theories have ranged from new system colors, new bundles, to a new system redesign. Hopefully, we'll see more when the PSP's second anniversary comes up on March 24th.