One of the things that I love about the Jewish religion is the importance of learning. When Jewish people study they don't just study with the people in the same room. Instead, they use a book that contains ideas, questiosns and answers from other Jewish people who have lived throughout the ages. A typical page of Torah, when it's written in a book, has several short sentences of the actual text, in Hebrew at the top right of the page. RIght next to the original text is a translation in Arameic from one of the great teachers of the Babylonian period, Onkelos. Typically, In the margin of the other side of the page, stretching below the primary text is a comment by a great French rabbi (1000s or so, I think), Rashi. The page also includes comments by a Spanish Rabbi (Mainmonides), and others. Take a look at what a page looks like: http://en.wikipedia.org/wiki/Image:Mikraot_Gedolot.JPG You can see all of the differnent comments.
So, you might be asking, what does this have to do with Web 2.0. What's Web 2.0?
Another way to look at Web 2.0 is that it contains dozens and dozens (likely far more now then when I began writing this sentence) of conversations. Each conversation starts with an original idea. But then lots and lots of different people from different backgrounds and different geographical regions chime in. Soon, as often happens with Jewish learning, you've gone off on such a tangent that it's hard to know how you got from where you were to where you are. But then again, does it matter?
The beautiful thing about taking a look at the page of text linked to above is that even if you don't read Hebrew, which I imagine most people don't, you can see the differentiation between the different comments. By the way, when I was a high school student I once hesitated about writing in the Torah (the book form of it). My teacher, a rabbi, looked at me and said, "Do you think Rashi (one of the rabbis who's words are found on the text) started off by having his ideas published in print or did he have to write them first?"