Yes.... MOST routers have the ability to do MAC Address filtering..
1st - Log into your Router.
2nd - Find MAC filtering page
3rd - Put in the MAC addresses of the computers that will use the rotuer (wired or wireless, and do NOT enter the PSP's MAC addresses)
4th - Apply filter to allow acces to ONLY the addresses listed
5th - MAKE SURE TO SAVE ROUTER CONFIG!!
On my D-Link router, this page has a drop down where you can select computers by name that are already connected to it (wired or wireless) and then it will automatically populate the MAC address.
If your router doesn't have this option, go to each PC that SHOULD have access, and perform the following... (assuming you use windows OS's)
START > RUN > type 'CMD' > type 'IPCONFIG /ALL'
The MAC address will be listed as 'PHYSICAL ADDRESS', and is a 12 digit number that looks like this:
Physical Address. . . . . . . . . : 00-13-72-0B-D7-34