Using Lightroom to Reorganize My Folders

 
Before using Lightroom 3, I had some sort of organization to the folder structure for my images.  Essentially, I had created separate folders for each month of family photos.  Lightroom 3 can do better than that - it can create automatically create subfolders for each year, and within that, each month, and within that, each date.  Moreover, during the import process, LR3 can rename the files with a date or other prefix (which I think is important to avoid having files with duplicate names). 

At the time I created my LR catalog, I knew that I wanted LR to create the chronological subfolders but I didn't know how to make it happen.  If all my files had been in one folder, then there would have been no issue.  But because I had already created folders for each month, LR would have created subfolders within each of those month folders, which would have been redundant and confusing.

Here's how I let LR reorganize my folders:
1. Before doing any of this, I made sure any metadata was saved from the catalog into the files.  Lightroom doesn't automatically keep the metadata in the files updated (for performance).  In my case I hadn't used LR before so there was no LR metadata to speak of for most of my photos.
2. In the Library module, I selected the folders to be reorganized.  I selected all the pictures in those folders (including subdirectories) then removed them from the catalog (not deleted them from the drive).  This step is necessary because LR won't import any photo that is already within its existing database.  I did this in small batches for safety.  Note: if you select a large number of photos, LR won't respond immediately - just give it time.
3. After the images have been removed from the catalog, go to import and re-import them (I chose "Move" to a newly-created folder), specifying that the files should be renamed and the chronological subdirectories should be created.  Reminder: don't rename files that have already been renamed :)

I'm a Lightroom newbie and I don't know if this is the best way to go about it but I haven't found instructions for doing the same thing elsewhere and this process worked for me.