I am working on a 'Web 3.0' book so I am having a lot of fun and extending my own knowledge on linked data and other Semantic Web technologies. However, when thinking about the evolution of the web, I don't think that distributed semantically enabled data stores are anywhere near to the whole story. The evolution of the web now coincides with a very large change in our world-wide society: a move to what I call the "great frugality" of value/production based society and economic systems. While I look forward to a world wide shift towards increased emphasis of local infrastructure (definitely food production, and when possible light manufacturing), the evolving web is what can still keep us connected both to friends and colleagues with the same interests and to potential business partners, no matter where we live.
A big part of a shift towards a value/production based Web 3.0 that combines material for human readers and linked business software systems is the reduction of cost through open source software. It is clear that when using and building highly distributed systems on the web platform that we need to take advantage of multiple platforms (Java, Ruby/Rails, PHP, Pyhton/Django, etc.) I noticed that IBM is releasing a new version of Project Zero that provides an integrated Java and PHP deployment platform. My personal platforms of choice are Rails and Server side Java so I prefer Sun's Glashfish/JRuby/Rails/Java bundle.
The point that I am making is that platform choice is often guided by what combination of major open source web application frameworks best fit our business needs. A secondary concern is how we merge and integrate applications like (for example) PHP based SugarCRM, Java Business Intelligence stacks, and custom Ruby on Rails applications.
The final piece of the "great frugality" is learning to live with and accept open source licenses like the GPL and AGPL that to a large degree forces the sharing of infrastructure software. This can be an expensive mistake: failure to take advantage of cost reduction from open software infrastructure, while gaining either competitive advantages or at least efficiency and profitability due to business processes and knowledge.