May NPD shows sales surge for PSP while all others decline

[JSF]

March 2007 vs. April 2007 vs. May 2007  

PlayStation 3: 130,000 vs. 82,000 vs. 81,600
Xbox 360: 199,000 vs. 174,000 vs. 155,000
Wii: 259,000 vs. 360,000 vs. 338,000

Nintendo DS: 508,000 vs. 471,000 vs. 423,000
PlayStation 2: 280,000 vs. 194,000 vs. 188,000
PSP: 180,000 vs.183,000 vs. 221,000

(Source: 1up.com)