During this revamp we were pointed to Creole by a community member and decided to give it a try. We liked it and decided not only to adopt it but to make it the default wiki syntax for all future version of Liferay (we still support an older syntax for backwards compatibility).

Some more information can be found in the following entry of my blog: http://www.liferay.com/web/jferrer/1/blogs/introducing_the_amazing_new_liferay_wiki