Not in Lion. PPC applications are not supported by Lion. You can try upgrading them to versions that are designed to run on Intel Macs. You can look for Intel compatible alternatives. You can partition your hard drive and install Snow Leopard on one partition that you can use to run PPC applications by installing the Rosetta emulator when you install Snow Leopard.
Beyond this it's hard to assist because you did not state what PPC applications you want to run.