Let me start by introducing a little bit about myself. I am the founder and admin of a few electronic trading card games wikis. The wikis I'm in are a bit different to the typical wikis as most of our pages are made up of information of in game cards, so most of our content pages are short and less than 300 bytes and we deal with a lot more data and numbers. It's sort of a different breed of wiki as most of the contributors are contributing by posting card stats and details instead of writing articles.
As we deal with lots of numbers and data, having semantic mediawiki installed on the wiki helps a lot is sorting out the data by sorting out the best cards by creating sortable card tables (example) to compare cards. Also because majority of our pages are card pages, i find the edit with form feature of the semantic mediawiki extremely useful. Here's an example where edit with forms make editing a lot easier especially for the newbies. Semantic mediawiki is sort of the backbone of trading card games wiki.
Recently I created the G.I. Joe Battleground Wiki (also a trading card game) and when i request for Semantic Mediawiki to be installed, I was told that "due to compatibility issues between SMW and Wikia, SMW will no longer be an option on wikis". And after further enquiries, it seems like Wikia do not plan to allow SMW on any additional wikis in future. It also said in the email that "If there are other tools that you could use that might help accomplish the same tasks, feel free to let us know and we can either enable it or, if it's not on Wikia yet, evaluate it for use on Wikia."
I hope Wikia will allow SMW in the near future as the wiki will be crippled without it and I'm not sure whether there are any extensions out there that will be able to accomplish what SMW can. I don't know a lot about the programming side of mediawiki, I hope some of you who use SMW or are experienced in codings to share your opinions and experiences on SMW.
P/S: This is my first blog on commuity central. =)