This is simply taking the time to think about all of the changes that may be occurring in the company - up and down and across many functions. You may also get good leads from information about a firm - and use it to find opportunities with their suppliers, customers and even their competitors. The obvious implications are that this company could very well need executives in marketing and sales. Since it's a new division, they may also have some need for people in production, logistics and other disciplines as well. Firms with problems can also be of interest.
Reorganizations involve shifts within executive ranks.
They usually spell opportunity for those who are at the next level, and then changes ripple down through the firm. If you are seeking a position as an executive, the CEO or a Board member will often be the logical person to contact. HR executives will also be aware of the openings in a company. However, the SVP of your major function is going to be a better alternative. Keep in mind that many employers undergoing major change are actually the smaller and faster growing firms, and they are far less constrained by hiring traditions.