As a general matter, the answers.com text does not adequately cover the concept of, and problems with, self-plagiarism.
There is an allusion to "least publishable units" in the answers.com text. LBE was using the term in the late 70's/early 80's, and a colleague even had a "unit name" for such things (named after a practitioner of publishing small segments.) For now, we'll call it the Jones, and good papers would have ratings in the realm of Mega-Joneses.
from answers.com :
Self-plagiarism (also known as "recycling fraud" ) is the reuse of significant, identical, or nearly identical portions of one’s own work without acknowledging that one is doing so or without citing the original work. Articles of this nature are often referred to as duplicate or multiple publication. In addition to the ethical issue, this can be illegal if copyright of the prior work has been transferred to another entity. Typically, self-plagiarism is only considered to be a serious ethical issue in settings where a publication is asserted to consist of new material, such as in academic publishing or educational assignments . It does not apply (except in the legal sense) to public-interest texts, such as social, professional, and cultural opinions usually published in newspapers and magazines.
In academic fields, self-plagiarism is when an author reuses portions of their own published and copyrighted work in subsequent publications, but without attributing the previous publication. Identifying self-plagiarism is often difficult because limited reuse of material is both legally accepted (as fair use) and ethically accepted.
The concept of self-plagiarism
The concept of "self-plagiarism" has been challenged as self-contradictory or an oxymoron .
For example, Stephanie J. Bird argues that self-plagiarism is a misnomer, since by definition plagiarism concerns the use of others' material.
However, the phrase is used to refer to specific forms of potentially unethical publication. Bird identifies the ethical issues sometimes called "self-plagiarism" as those of "dual or redundant publication." She also notes that in an educational context, "self-plagiarism" may refer to the case of a student who resubmits "the same essay for credit in two different courses." As David B. Resnik clarifies, "Self-plagiarism involves dishonesty but not intellectual theft" 
According to Patrick M. Scanlon :
“Self-plagiarism” is a term with some specialized currency. Most prominently, it is used in discussions of research and publishing integrity in biomedicine, where heavy publish-or-perish demands have led to a rash of duplicate and “salami-slicing” publication, the reporting of a single study’s results in “least publishable units” within multiple articles (Blancett, Flanagin, & Young, 1995; Jefferson, 1998; Kassirer & Angell, 1995; Lowe, 2003; McCarthy, 1993; Schein & Paladugu, 2001; Wheeler, 1989). Roig (2002) offers a useful classification system including four types of self-plagiarism: duplicate publication of an article in more than one journal; partitioning of one study into multiple publications, often called salami-slicing; text recycling; and copyright infringement."
**Some relevant IPBiz posts