Sony updated the PSP the 2nd time now. Nintendo only updated the DS once until now, but still outsells the Sony portable Playstation.
In August Nintendo sold 518,300 DS consoles. Sony only made half that number with 253,000 PSP consoles sold in the United States. The PSP number is actually not that bad considering a new PSP has been already announced.

The new Sony PSP is the PSP-3000 model, which Sony announced in August, but shipping starts actually in October.
The Sony PSP-3000 features an advanced LCD screen supporting higher image quality, crisper colors with more definition when outside in natural light. The PSP-3000 also includes a built-in microphone, maximizing the communication features of products such as Go! Messenger and Skype.
The Ratchet & Clank: Size Matters PSP Entertainment Pack will feature the new PSP-3000, which is available for pre-order on Amazon.com.

Sales numbers via this Reuters story.