Not a big deal, but I'm not a fan of the changes to the Links functionality in the admin section in 2.1 First off, I'm not a huge fan of the word "blogroll." It's somewhat dated and not always applicable to how people use WP. So changing the name of that tab and section from Links to Blogroll is not welcome.
But I find it especially perplexing why you moved the links/blogroll category mangement to the Manage->Categories tab. It seems as if you've disconnected two things that belong together - the ability to manage the links catgeories. I'm curious about the thinking behind this.