From his Yahoo page:
Apr 15 ESPN.com reports Pittsburgh Pirates 1B/OF Craig Wilson is expected to see the majority of the playing time at first base with 1B Sean Casey (back) out with a back injury.
Wilson's historically been a fast starter who is also capable of fading in epic fashion later in the season. Casey's supposed to be out as long as two months, which is just about the right run for Craig.
I don't know if I'd waive Preston, but I'd definitely shed mediocre bench fodder (and have) to give CWilson a crack at a job.