Over at Rays of Light Jon Wolfson has posted a story about how Longoria is a longshot of making an appearance in 2008 based on Matthew Silverman's comments:
According to Silverman, Evan Longoria will most likely spend the entire 2008 season in the minors, barring injury or a performance at Durham showing beyond a doubt that he can succeed at a Major League level.
Oddly enough at the same event Silverman told Matt Garza that their plans have changed on Longoria's call-up date from "late season" to "very soon". This is simply posturing to get fans off of the team's back and smother the outrage.
I've posted what I've heard, that being after around 20 games Longoria will be up, it's simply about getting the extra year while allowing Evan to develop just bit more. The team is following the model set by the Brewers last year in hopes of duplicating Braun's early success.