This is a popular thread in that it's always at the top. I've been fascinated by Bitcoin for for over a year, and have decided to join bitcointalk.org to get more involved.
I see Side Chains as more interesting than gold and would really appreciate a summary of the pros and cons they have for Bitcoin.
Why is this even a debated topic?
Probably because some people became invested (financially and/or emotionally) in various strategies which were predicated on certain expectations of how Bitcoin would overcome it's rather obvious weaknesses and did not anticipate sidechains as being one of them.
In this respect sidechains are every bit as much of a 'disruptive technology' to Bitcoin as Bitcoin is to the mainstream debt-based monetary system. Naturally some people will lose, but they won't be going down without a fight.