This is the fourth novel in the Walker Papers (see also Urban Shaman; a novella; Thunderbird Falls; and Coyote Dreams), featuring a Seattle policewoman with mystical powers; it won't be published until next year, but mizkit kindly let me have sight of it. NB that she has been posting short stories on her livejournal this last week, including another Joanne Walker one yesterday.
I've described these books before as being slightly in the Buffy mode (and if you like one you'll probably like the other). One difference, though, is that Joanne is part of the normal system of authority, rather than revolting against it in the way that Buffy does. However, mystical powers and police procedure are not easy bedfellows, and a lot of the tension underlying the narrative comes from her (and to a lesser extent her colleagues) attempting to reconcile her two roles as shaman and detective. I think this book explores this interesting side of things rather more than its predecessors.
In Walking Dead, as apparently it is to be called, Joanne is called on to investigate the disappearance of an ancient cauldron, and soon finds herself dealing with the consequent undead zombies, calling on mystical and human (and half-human) allies to find the person responsible, while also dealing with her mildly messy personal life. As ever, both the mundane streets of Seattle and the supernatural forces spilling into them are vividly imagined, along with Joanne's more personal dilemmas. Fun.