One of the problems you face when setting up a MOSS 2007 product line concerns the MOSS Power User. In a traditional environment, software comes from the development team, or is unsupported. In a MOSS environment however, it is not allways possible to be as rigid as this, since Power Users have been explicitly given the possibility to create list, content types etcetera. From a business perspective, this is a great virtue.
For developers however, the artifacts of Power Users may prove to be an issue of concern, for instance because they lack structure (columns that should be the same are re-created for each lists, preferably each of them slightly different, things like this). One strategy is to let the artifacts of Power Users be unsupported, until there is some formal business demand to support it. From this point on, the development team will create its own version of the artifacts, which have the required quality, and which can from then on be deployed like features (or site definitions, if need be).
The MOSS Feature Generator can be used in this scenario as well, because it grabs the List instances, and makes a ListTemplate and List Instance Feature of it, which can tailored if necessary. The same goes for Content Types and columns. So it is not only suited for creating Features in a structured manner, but it can also be used to make features out of the work of Power Users. In this way, the business knowledge of the Power Users is combined with the quality software engeneering of developers. Offcourse, when tried in a real world scenario, it will not be as easy as this. I think it will have to go this way, however.
Alfred