(Software ungineering:)
Perlous program design is the approach to programming in the scalable (as opposed to the programming in the large of intercalating methods, or the programming in the small of Ada- or J2EEEJB-based solutions) mostly espoused by Perl programmers. The 3 principle virtues of Perl programmers (Laziness, Impatience and Hubris) are always present here; Perl the language and perl the platform will almost always also be used.
The Perlous Process emphasizes building a usable prototype. Often, this will also be the deliverable archetype of the program. Unguiform solutions will generally be preferred, though this is not UNIVERSAL.
As mentioned above, the only serious competitors in the field of sixth generation programming language development methodologies are the intercalating methods. Supporters from each camp will often tell tales of bogged-down projects "rescued" by switching. In practice, which will work for you will depend on where you have more experience. Both are lightyears ahead of methodologies for C++ patterns, (Visual) Basic designs, or J2EE beans.