I'd highly recommend other volunteers attend this. Wikidata's a very exciting project and it's evolving rapidly, but the interface is different from other Wikimedia wikis. Not harder, just different. Even if you're familiar with both wiki editing and databases, there are new skills to learn. Then again, because it's a different interface, it puts newcomers and experienced wiki contributors on a more equal footing.
Since attending last year's workshop I've made some, but not a lot of, edits to Wikidata, but I am in a much better position to explain and evangelise Wikidata to researchers, librarians and academics.
To those of us involved with it professionally, it's obvious that machine-readable linked data is centrality to what the web is meant to be (including in Sir Tim's design), and plays an central role in making knowledge *freely* available, including freeing up knowledge in other databases. This isn't at all clear, though, to the vast majority of the population who don't have those nerdy jobs, and that includes the vast majority of Wikipedians. So I think it's good for Wikipedians to familiarise themselves with Wikidata (or DBPedia) as a concrete example of what the semantic, machine-readable web can be: to think of the web as interlinked data, not just interlinked documents.
Magnus' Reasonator is a thing of beauty and an educational joy - it's definitely worth spend some time playing with it. Even better to speak to the man himself!