By default, in Finder folders are shown in between all other files. alphabetically. There was a hint for Snow Leopard that showed how to show folders first in Finder, which is not working on Lion. This is because of the file:
It is now a binary file, instead of an XML text file.
You need to convert the file from binary to XML, using this Terminal command:
sudo plutil -convert xml1 /System/Library/CoreServices/Finder.app/Contents/Resources/English.lproj/InfoPlist.strings
Now you can edit the file, using:
sudo vi /System/Library/CoreServices/Finder.app/Contents/Resources/English.lproj/InfoPlist.strings
Find the following section in the file:
Then add a space in front of Folder on the second line. You should now have this:
Save the file, and convert it back to binary with the following command:
sudo plutil -convert binary1 /System/Library/CoreServices/Finder.app/Contents/Resources/English.lproj/InfoPlist.string
Restart the Finder and now folders will be shown at the end. I am not sure why they are at the end and not at the beginning.
I haven't tested this one. As always, make a backup copy of the file before making changes, and be aware this may cause code signing issues.]