The Wikibooks logo is an issue that needs to be decided, but which can't seem to draw anything besides complete apathy from the community.
The current wikibooks logo has a number of problems which are often sited as reasons why we need to change:
1) The "flower symbol" on the front of the textbook (frequently taken to be a diagram of an atom) seems to show that Wikibooks is biased towards science books, chemistry books in particular. Considering that the first Wikibook was the [[Organic Chemistry]] book, it's easy to understand why this might be the case. Wikibooks does have a rich set of textbooks from across the educational spectrum, and the "atom symbol" really isn't appropriate.
2) The unofficial slogan, "Think Free, Learn Free" really has no basis in the Wikibooks project itself. It is a nice idea, but I've heard tell that it's difficult to translate. Also, "Thinking Free" isn't really one of the goals of the project at all. It would do better as "Teach Free, Learn Free", or "Read Free, ...", or something similar. While we are a free content website, our primary focus is on structured instruction, not free-form thinking. I would love to have an official wikibooks slogan or something, but this isn't it.
3) The logo is relatively poor quality, even the newer SVG version of it. It also isn't as aesthetically pleasing as most of the other WMF logos are. In fact, in terms of it's design, I would say it's one of the worst logos on the internet. Thankfully, you can't judge a book by it's cover.
There was an effort to replace the logo that was moving along very well on meta. At the last stage of the vote, we hit a stumbling block because it was decided that the logo could not use the standard WMF colors (green, blue, and red). The logo that had been selected used these colors, so an impromptu additional round of voting was started to try and select a new colorscheme for the logo. This, of course, brought about a new wave of criticisms, because many people said the vote was invalidated, or that people would not have voted for the selected logo if it had been in different colors. At this point, the discussion was all but aborted.
A new round of voting was started recently, asking people to vote to continue the process and move on to the next step. While there is majority support for this new round, there are a few vocal dissenters who think that we need to either abandon the process entirely, or restart it all from the beginning.
What would be nice is if we could get this process on track, but there is so much confusion, and so much apathy from various community members that we just can't seem to move forward.