A little belatedly, but I thought I might provide an introduction to the namesake of my little blogthingy I got going on here. I'm simply going to present what I take to be Pirsig's main philosophical suggestions.
Pirsig's first book, Zen and the Art of Motorcyle Maintenance, presents his "Quality thesis". This thesis has many sides, but it comes out of a reaction to the dominant subject/object distinction in post-Cartesian modern philosophy. Pirsig sees quite rightly that if we dissolve the dichotomy between the knowing subject and the known object that we end up with a play of values. Pirsig's way of getting there is to attack the Greek idea that our primary relationship to reality is one of knowing. Pirsig asserts, rather, that our primary relationship is one of valuing, and that everything else falls from there.
What this thesis ends up meaning from "there," however, is disputed to a certain extent. Some people are content to follow Pirsig in offering a broad, general onto-cosmological view of reality centered around the undefinable "Quality." I consider such views to be occasional poems with a determinate subject matter that are potentially beautiful, but generally shouldn't be taken too seriously. Because if they are taken seriously (as Pirsig and most of those who do write and enjoy such poetry), they turn back into the Platonic philosophy of knowing that Pirsig was trying to get rid of. When it comes to philosophical theses (of the kind that get bandied about in professional circles), Pirsig should be seen as only offering negative ones against a predominate image of philosophy--Subject-Object Metaphysics.
One of the theses that Pirsig presciently sides up with in ZMM and continues in Lila is that of historicism. Pirsig suggests that we are situated in history, in a continuing conversation with "ghosts of history" that produces what we call knowledge: "the building of analogues upon analogues upon analogues". In the cosmological poem to reality that Pirsig offers us in Lila, he adds an important nuance--the distinction between static and Dynamic. Our static patterns of value are broken by Dynamic Quality, those crazy new things that we sometimes just instinctively feel are better. If these crazy new things end up being better, then they leave behind in their wake new static patterns, which eventually become the new crust of convention that Pirsig, like Dewey before him, suggested we should always be ready to break through.
The importance of the connection between Pirsig's Quality thesis and his historicism is that the move from knowing to valuing moves us from essentialism to relationalism. No longer do we have objects with an essence that we can know. Instead, we have "objects" that are constituted by the layerings of value placed upon them. And since any "subject" doing the valuing is also a collection of these layers of placed value, we invite a kind of panrelationalism in which any "object," or "subject," or more generally, any "thing" we differentiate from any other "thing" is defined by its relations to every "thing" it's being differentiated from (including what's doing the differentiating).
This is why the static/Dynamic distinction becomes very helpful in Pirsig's later philosophy. All objects are static patterns of value of some kind. A static pattern of value is a repetitive way of valuing some "object," but since all there is to this "object" are those repetitive valuings, we call the locus of those valuings the "object" and name it, e.g., a "rock" or a "molecule" or an "electron." However, the relations between things change over time. Sex changed biology. The Greeks changed politics. The Romantics changed the way we create ourselves. All of those things changed the way things were previously done and are retrospectively viewed as progressive (namely because they allowed the other things after them to occur). But more importantly, we must become historicists after renouncing essentialism because essentialism held up the ideal of being rational by correctly identifying objects with particular amounts of intrinsic value. By rejecting essentialism, we reject the idea of intrinsic value and so reconstitute the process of valuing (and the rationality of it) as an historical process of advancing betterness. A break in the old patterns of valuing is defended, sometimes only retrospectively, by the betterness accrued in the new patterns, and betterness can only assessed by other old patterns being left in place. Eventually, it is theoretically possible that we may tear down so many of these old patterns that there are none left that we could identify with, essentially making us a new form of life. But as long as we can tell a story of progressive betterness, of how we got from there to here, we can be rational and avoid the charge of nihilism often attributed to those who deny essentialism.
There are a lot more facets to Pirsig's philosophy, and even more to his writings. But I take the above to be basic to the position in philosophical space that Pirsig occupies. While I don't think a whole lot cosmologically follows from the above, I do think think that it breaks down Plato as Pirsig wished to do.