Long but well written and thought through discussion on SOA (Service Oriented Architecture) and Web 2.0 (simple, user centric) 

Rather than focus on the differences, I think it’s more productive to focus on where the two are similar. What SOA and Web 2.0 have in common is that they both represent a similar shift in approach – a break with the technology and application centric practices that we’ve live with for so long, to focus on how technology is used. Both enable a user centric approach to IT.

Source: CTO Blog | SOA & Web 2.0: Cage Match

The thrust of the piece is that SOA comes from the system, product end, and Web 2.0 comes from the user, so the right approach is to seek synergies in how the two work together from optimisation.