TwicI (for which TwiciWiki is a WikiName) is a fairly simple wiki written as a suite of perl CGI scripts. It is undergoing fairly quick evolution, but is and will remain simple and not very featureful. Its development focuses on preserving the WikiEssence. Some notable features include:
An aggressive WikiName pattern which allows internal capitals; as well as PopeOnARope, this makes TwicI and SF into WikiNames
A simpler and (arguably) more intuitive page formatting language than WardsOriginalWiki, based on mail/news conventions
HTML 3.2 compliant output (mostly!)
A MessageOfTheDay page to communicate system information (this is a social convention rather than a technical feature, but it's something that the author felt was not handled well on WardsOriginalWiki)