I use conifer needles and mulch around my Blueberries and other acid loving plants. As long as the plants do not need alkali soil PH levels then use them as a mulch.

As Kildermorie says, use around acid loving plants such as Pieris, Rhododendron, Skimmia, etc., but I wouldn't use them around things like roses. And I certainly wouldn't use uncomposted chippings anywhere at all other than on paths at an allotment or somewhere. Using chipped fresh/live wood means it'll steal the nitrogen from the soil as part of its breakdown process - and your plants need the nitrogen. Compost them first.

Fresh chippings can be used as a weed suppressant on places such as paths or round shrubs provided that there are no other plants growing in the area. Old, composted chippings are ideal as a surface mulch for ericacious plants and I haven't found a problem in using them around other plants either. Probably better to avoid real lime-lovers though.