More like eight directions to me Bob.
Actually, I believe it refers to the 'four main powers' (peng, lu, ji, and) and the four additives powers thereof.
Eight historically recorded "powers" or methods. This word, powers, is a poor translation of the original word in Mandarin, "JIN" which has many meanings of course, some of which relate especially to martial arts.
In the martial arts, JIN means basically, power. It can also mean simply strength as in someone has a lot of strength. In the case of internal arts the meaning of "Jin" that we specifically use is that of a trained or cultivated strength or power. This refers to the power (or even utility) that manifests in a practitioner due to training, or simply in a specialized manner.
What do you think 8 powers refers to, Graham?