Unfortunatly not, but it is planned for HFS 3
In the meanwhile you can add a folder as a virtual folder and when you wish to update it, right click it and select <switch to real folder> and then right click again and select <switch to virtual folder>.
Rejetto I think it would be a good idea to have a folder menu option that updates virtual folders that are bound to real folders. It shouldnt be too hard, but if you rather wait till hfs 3 I and everyone else can use the method I described above.