It was a little odd when Sony appeared to drop the price of the PSP Go from $199.99 to $149.99 on the official PSP site on March 4, without an official announcement. Especially curious was that retailers of the device weren't also adjusting their on-site pricing.
Since that time, the PSP Go price on the official PSP site has reverted back to $199.99, without any real explanation from Sony. (via Joystiq)
It's unclear as to whether the PSP Go will see a price-drop (that actually sticks) in the future. That said, the PSP-3000 just received a $40 price drop not too long ago, and the release of the next-generation of handhelds (NGP and Nintendo's 3DS) are right around the corner. It seems like the ideal time to start discounting your older hardware, just on general principle.