Since November 6, the Library tab has functioned slightly different in that, when you click on the Library tab (a sub tab from the "Academics" top-frame tab), the page will load in a new browser tab.
I know many of you keep your pop-up blocker settings on and always vigilant to protect your computer from annoying advertisements (remember, if a popup says you've won a new iPad, chances are, you're just going to win some malware and a headache if you click on it).
If you keep your pop-up blocker on, make sure that you pay attention to your browser when trying to open the Library tab because it will most likely prompt you to disable pop-up protection for this page in particular. Disable your pop-up blocker for this particular page and everything will work as you would have expected.
On a side note, I want to point out that the Tech Support top-frame tab within Blackboard contains a subtab called "Library Passwords" where you can get the username and passwords to many Library related resources.