Well, Rick (Riordan) recently announced that the series was talking a new look. It was first announced by the Percy Jackson Page which posted a sneak peak on Facebook and then by RR who reposted the sneak peak with a link to the Percy Jackson Page on FB.
Percy Jackson Page Post:[]
"Percy Jackson & the Olympians is getting a new look! Stay turned for the reveals next week...
5days. 5 brand new covers."
[Image of the sneak peak]
Rick Riordan's Tweet:[]
Percy Jackson & the Olympians gets a new cover treatment from John Rocco, who did the original art. 1st sneak peek: https://t.co/x1Qo5bYUAS
The Lightning Thief[]
2/17/14
The Sea of Monsters[]
2/18/14
The Titan's Curse[]
2/19/14
The Battle Of the Labyrinth[]
2/20/14
The Last Olympian[]
2/21/14