I think it depends on the business model.

I've seen a strong correlation in some areas, where the entrepreneur's business relied on lots of contacts and sales through contacts. But I've also seen success by what you would consider non-social types, the sort that go into a hole, work their tookus off, emerge with something valuable, then sell it through non-social methods like online and mail order.

The strongest entrepreneurships I've seen combine different people with complementary skills.