Well, its difficult to say and I'm not going into the details, that's what wikipedia is for, but basically its a way of describing a theoretical 'new version' of the internet. To me at least, its talking about an internet that isn't just consumed by everybody but can be easily created and changed without esoteric knowledge about Java, C++, html or any number of other scary abbreviations that are almost meaningless to the majority of the non Star Trek loving population of the planet (not that I have any problem with Star Trek).
Essentially it's sites like YouTube, Facebook and and Flickr which allow you to interact with the web, create your own space and interact with other people online. Sites like Weebly (the service I use to publish this blog) and Google Apps allow web publication without ANY programming knowledge. Basically if you can use a word processor you can now have a presence on the net.

Web 2.0 has huge potential to change the way archaeology is viewed in Ireland. Dissemination has been one of the buzzwords in the discipline for the last five years but I have heard little talk about how the internet can transform how we disseminate to the public. The potential to reach out to the public, to inform and, excitingly, to interact is gigantic.
Irish archaeology's response to the internet has been mixed. Some interesting and useful steps have been taken with online bibliographies, databases and mapping (e.g. Archaeology.ie, Excavations.ie, EMAP) but these are generally aimed at those already interested and they aren't exactly user friendly. Many commercial sites provide summaries of excavations, some make reports available and one even has a blog (not that it is much used). However there are plenty of very basic commercial sites out there and some of the archaeology pages on the internet I most use (Thadeus Breen's and Conor McDermott's sites) are still decidedly web 1.0.. Academia has done little more and the University webpages are nothing if not boring. Where are the academic blogs? The rich video and audio content or the electronic publications?

Hopefully I'm not coming over too preachy and I am aware that this site and its subdomains (smelt.seandalaiocht.com and charcoal.seandalaiocht.com) are by no means perfect but they do show some of what is possible with no programming knowledge, practically no money and a bit of time. Future plans for the site include a database of Irish iron sites based on my PhD research, an interactive map of the same and more articles, presentations, videos and photos. There is nothing stopping any other archaeologist starting a site and sharing a little of what they know and are interested in with the public who ultimately pay their wages (or, more likely these days, their dole!).
The move to better websites in Irish archaeology is already noticeable with the trend for almost every INSTAR project to have a website (for a list see here) and the recently updated Discovery Programme pages. However we can do more. Sites like Scribd and Issuu make it free to publish online; Google and Bing's mapping services offer the potential to create accessible geospatial data at no cost; and Youtube and Vimeo do the same for the distribution of video and audio.
Lectures and books are not the only way to tell people about archaeology. We don't need to make it more interesting, we all know its already fascinating, but it would do no harm to make it all a little bit easier for the man on the street. Call it benevolent self-interest: the more people get interested in archaeology and value it, the more chance they'll be happy to fund it.