I just installed Lion, and I can't find the Library folder in my user folder.
Does the folder no longer exist? If it doesn't, where are my preferences? If it does, how do I get to it?
The ~/Library folder still exists, but it is hidden. You can easily unhide it by running the following command in Terminal (/Applicatiions/Utilities):
Note that you'll have to do this again after each 10.7.X update (credit to Vincent).
If you want to reveal it on a per-use basis, you can get in by holding down option and clicking on the Finder's Go menu.
The app Lion Tweaks gives you an easy GUI way to change this setting, as well as other hidden Lion preferences.
Set the Finder view to Columns (just for this exercise. You can change it afterwards).
Close Finder windows.
Hold Option key while going to Go in menu bar and selecting Library. This opens a Finder window with the word "Library" in the title/name location at top center of window. Release option key.
Click and hold the folder next to "Library" and drag it into your sidebar where you want it. Release.
It will stay there until you Command-Drag it out, no matter how many SU for the 10.7.x OS you get.
The ~/Library folder is still present but is "hidden" in OS X 10.7 by default, however there are a variety of ways to access ~/Library, depending on how frequently you need to access and on whether you want it to remain hidden.
The best summary of these methods is found at 18 ways to view the ~/Library folder in Lion.