What is product line software development? Are there any journal articles available?

Hello, jonjin:

You can find a lot of information about Product Line software
development on this page:

Product Line Approach to Software Development
http://www.sei.cmu.edu/plp/plp_init.html

You can get a very nice overview here:

Software Product Lines
http://www.sei.cmu.edu/plp/product_line_overview.html

"A software product line is a set of software-intensive systems
sharing a common, managed set of features that satisfy the specific
needs of a particular market segment or mission and that are developed
from a common set of core assets in a prescribed way."

"Organizations are discovering that a product line of software
systems, when built from a common set of shared assets, can result in
increased market share, lower staffing requirements, significant cost
savings, higher system reliability, greater customer satisfaction, and
shortened time to market. Organizations pursuing the product line
approach for software systems can enjoy a significant competitive
advantage in the marketplace."

Regarding the documentation you ask for, here is a lot:

Product Line Practice Publications
http://www.sei.cmu.edu/plp/plp_publications.html

I hope this is what you were looking for, if not or do you want
additional information, please, don't hesitate to request for a
clarification, I'm here to help you until you get what you need.

Search strategy

"product line" software development
://www.google.es/search?hl=es&ie=UTF-8&oe=UTF-8&q=%22product+line%22+software+development&meta=

Regards.