I hear several people either splash decanting or using a decanter that maximizes oxygen content in several, especially new wines. Every time I bring a decent bottle of wine to a restaurant (the oldest in my cellar would be 00/01's)the sommeliers give it a slow, methodical poor. Are there guidelines for decanting wine differently to maximize taste perhaps based on bottle age, wine style etc... or is the sommerlier just trying not to be ... sloppy?

i usually pour it slowly down the sides, and it seems like that allows maximum air exposure without being rough with the wine. the only downside is you have to watch the sediment or you'll have half of the decanter covered in dirt

Depends on the wine. These are my general guidelines:

If it has thrown a lot of sediment or has other weird gunk in the bottom of the bottle (I check with a small flashlight shined through the bottom of the bottle), pour it slowly to avoid disturbing that stuff, stopping and discarding the sediment and gunk before you pour it into the decanter. Once that's done you can double decant the wine, pouring it back into the bottle or into another decanter to maximize the exposure to air.

If the wine is very old, it generally should be decanted carefully, not only because of the sediment but because the wine itself may be quite delicate. In fact, decanting really old wine is often best avoided.

If the wine is young and free of significant sediment, pour it fast and into the middle of the decanter to expose it to as much air as possible.

Gonna have to agree with Doug's recs here...when older, you don't want to agitate the wine. But with a youngster that needs air, let it rip right into the middle of the bottom of the decanter. And don't be shy with swirling the decanter vigorously...