I've always kind of dug it when a band uses the same artist for their cover art from album to album, so I appreciated it when I noticed that grunge-y locals The Passenger chose to keep Dutch artist Lobke Van Aar on board for their sophomore album, "A Dog Named Bear." According to their Facebook, they'll have the album out in January 2013, but here's an early look at the art.
Probably the most famous example of a band staying true to the artists responsible for their cover art would be Pink Floyd and Hipgnosis, or really, any band from that era and Hipgnosis. Then of course, there are bands who are more true to a concept than a particular artist, like Black Moth Super Rainbow who maintained the weird pumpkin-mask imagery on their last few covers because as Tom Fec said in a recent interview, "... I think the album cover and the picture and the mask and anything we’re doing helps shape what you’re hearing in some way, it gives you a little bit of reference ... ."
Whatever the philosophy behind choosing an artist or an image for the cover art, I think it's admirable to continue to acknowledge that album art still impacts the memory and connection fans feel to particular records. Even if many (I hope not too many) people only barely recognize it as the thumbnail used in their iTunes.