Expand symlinked directory in finder
One solution, as detailed here, would be to use a hardlink for the directory. It's very important that you understand the implications listed in Bob's answer as well as only use the hunlink utility (also in Bob's answer) to remove any directories created via the hlink utility.
I certainly would not recommend this solution for anyone who isn't comfortable understanding the details laid out in Bob's answer and/or for a shared system where not every user is aware of which directories are hard links and how to properly handle them.
The answer is no, there is not a way to get the nice little triangle to easily expand a symlink directory in the Finder's list view.
According to "Folder Aliases in Dock or List View cannot be expanded?" on SuperUser, "This is a known bug and is even mentioned in John Siracusa's review on Snow Leopard."
This is consistent with this Textmate Thread which discusses the issue without finding a solution.