1. Jump to anchor
1. This makes large wiki pages usable and allows users to quick find what they are looking for.  If you have a table that is quite large and broken up into sections, it helps to have a section listing at the top of the page and be able to jump down to the section by clicking on the link.  This could also be expanded as a way to autogenerate a TOC at the top of the page based on the anchor tags found throughout the page.
2. Templates
1. If you plan on creating a culture around using a wiki, you MUST have templates.  It really takes the wind out of someones sails when they have created a really nice looking page that could be used over and over but come to find out the only way to duplicate this work is copy and paste the code.  Being able to have a library of templates to choose from when creating a new page saves alot of time and allows a company to come up with a standard for how a particular type of page is suppose to look.
3. Ability to edit sections
1. There comes a time when you will need to add more than one section to a wiki page.  Anytime you create a new header you are telling the user, this is a new section of text that stands alone.  In large pages, if you have to deal with editing the entire page to get to the section you want, it becomes cumbersome and confusing due to the amount of text you must sift through.  If you can edit just the section you are interested in, it helps the user focus on the changes at hand and not worry about the wall of text in front of them.
4. Discussion for each page
1. When users make changes to a wiki page, there may be questions about the edit or challenges to the content.  You don't want to put this in the wiki content page itself and it's sometimes inconvenient to email or IM someone to resolve the changes.  To foster communication around each page in the wiki, it's best to have a place to discuss the changes right at the user fingertips while on the page.  The Community Kit for SharePoint 2007 was a step in the right direction but this really should be built into the product.
5. Markup
1. While having a WYSIWYG editor is nice, being able to quickly type something out can be just as useful.  While I think it was said that this might not make it into 2010, I really think unless your editor is top notch (the 2007 editor is far from top notch) you should support the ability to use and/or define a markup language.

I hope I have provided some useful feedback to the powers that be and hope to see some of the changes outlined here.

Shane