Mike's description is good and correct. I would like to add that compared to the shotgun approach, a bi-wire speaker cable that's one cable split as Mike describes is has virtually no benefit. You would probably be better off using a speaker cable of the single/split variety as one. When the conductors are this intimate in a single jacket, there's too much field interaction. The shotgun approach eliminates this and is in good part why it works. The former, I believe, is a good part of why bi-wire cables get a bad rap on occasion. There are other factors to consider also but, as for the cables themselves, shotgun is the way to go.
Further, the performance hierarchy is as follows:
1.) Bi-amp/bi-wire shotgun (as a side not, all Shotgun is bi-wire but not all bi-wire is shotgun. just another way to look at it.) It's possible to use two stereo amps or four mono blocks to comprise this arrangement. This is the best.
2.) Mono blocks or stereo amp/bi-wire shotgun. Next best and can be substantially less expensive but with the cost of some speaker cables, who knows? Performance can be very close to number one.
3.) Mono Blocks or stereo amp/bi-wire non shotgun. Forget about it. Save your money and buy more music.
Thanks for asking the question. I'll send you a free CD (see best interconnect you have tried thread).
Hope this helps a bit.