Check out some linux forensic tools that might be able to help you recover the lost data. Trouble is, the index for that data is erased and the OS considers that space to be free memory. It is quite possible that the location on disk that was deleted has been over written by some other program or data.
for a program that could possibly help. Oh and if they do help, there is a paypal donation button on the page that you could use to easily thank them with
Some of the things that can safeguard against this in the future is, aliasing rm with rm -i.
Also, backups, backups, backups.