Coach:

This was sort of covered in this thread:
[url=http://www.flyanglersonline.com/bb/Forum1/HTML/015066.html:31170]http://www.flyanglersonline.com/bb/Forum1/HTML/015066.html[/url:31170]

Even though most single action fly reels can be considered center pin reels; the term actually describes a reel designed for float or bait fishing on a conventional rod.

Some web links inaccurately point to a dealer's fly reel page if you do a search of "center pin reel" but if you read the descriptions they will talk about float fishing.