Business Development

So, how does one actually go about getting into a business development type position.  I don't even necessarily mean internal M&A with a big corporation.  I'm talking more about working for a company and developing new business.
 
ie.) Working for a military contractor and lobbying for new contracts
 
or
 
ie.) Working for a corporation and growing a new product line
 
Any stories or ideas about how one goes about doing this sort of thing post-banking would be appreciated.  Do you use a headhunter as though you were going for PE/HF or is it altogether different?