Design stencils would make it easier to use your patterns in design. For example Yahoo! provides a stencil kit which is mapped to the patterns in their library: http://developer.yahoo.com/ypatterns/wireframes

Add a new section to all pattern, which discusses the usability of each pattern. Something more descriptive than "Why?" section you already have. That would give more credibility to your patterns and would help people to decide whether to use or not to use a pattern.

You should let people use Sass for their CSS pattern libraries and maybe even have a place for Sass variables.

I believe that faceted navigation approach would make finding patterns easier.

Should be able to search for patterns by keyword.

Adding multiple examples to the same library at once makes it easier to add patterns, so the libraries wil get more great examples as well

Instead of sending invites to users, company employees could sign up with their company email addresses to access their company workspace.

I want to be able to say things like this can be a 'a' tag or a 'button' tag without it trying to make a link on my page. Super annoying!

I want to comment the whole private pattern library, not just the patterns. This should help in communication.

I created a pattern in a private library, realized I couldn't share it, so I went and entered my paypal information, got a shared account, invited people, and now I can't import my private patterns? What the heck!

1) Use phantomJS (or some other fancy stuff) to generate an image from the HTML I use in the case I don't give you a thumbnail image.
2) If I give you an image, make it the thumbnail by default.
3) Let me drag and drop an image.

Most patterns are related to other patterns, it would be nice to use an already uploaded image for another pattern as well.

I'd like to allow visitors add tags to patterns other users have written.

I want to be able to track changes on patterns and libraries as well as the latest comments.

Rather than simply having a list of code snippets in the order in which they're written it would be nice to be able to sort them alphabetically or categorise them to make for easier scanning/searchability.

This should be a no-brainer. I want to invite friends & colleagues to use this tool, but I don't see anywhere to do so. This is definitely the type of app where that would make sense. I see where I could invite colleagues to a shared workspace, but I suspect as a product, design and dev team we'd want to try the product out individually first.

It'd be great if you added an option to print your library so you can have it always at hand, comment on it and share it with your team :-)