I missed this until reading it on Rotisserie Baseball Musings, but PETCO Park will have the right center field wall pushed in from 411 feet to 400 feet.
My Google-fu turned up this MLB.com article:
The major benefits probably will be psychological, giving left-handed hitters a sense that they have a legitimate shot at going deep in what has come to be known as Death Valley.
While the impact won't be profound -- this is still a pitcher's dream park -- it will reduce some of the physical strain on center fielder Mike Cameron and right fielder Brian Giles. And, over the long, hot summer, that can be meaningful, given the huge roles both veterans will play.
I'm not sure I buy the "reduce the strain on Mike Cameron and Brian Giles" argument very much -- what's the benefit, watching balls sail over the fence instead of having to go after them? That's going to help the team somehow?
Theoretically this could help left-handed hitters like Brian Giles, Ryan Klesko and Terrmel Sledge, and Rotisserie Baseball Musing seems to think it might be enough to help the right-handed Piazza, given his opposite field power.
Yeah, it's January, but for those baseball fans, it's something to think about.