Just found this in
http://www.macgurulounge.com/library-folder-mac-os-lion/
To make your Library folder permanently visible, follow these steps:
Launch Terminal from the /Applications/Utilities folder.
Type this single line and press return to make the Finder visible again. This assumes you are logged into the account in which you want the Library to become visible:
chflags nohidden ~/Library
Now you should be able to see the Library folder from within your user folder. I would highly suggest you drag the folder to the Favorites section of the Finder Sidebar so that you can quickly access the folder. Even if it becomes invisible in the future (say, through a Mac OS X system update), youll still be able to access it from the Sidebar.
P.S. Based on my observations, if you are upgrading from Snow Leopard, and you had placed the Library folder in your Sidebar, the Library will remain there even after the upgrade. For you lucky people, this tip may be unnecessary.
There's more on the page, but this does it for me.