Yes, provided that each spoke's subnet is included in the network lists sent to each other spoke. Remember that the PIX will only forward traffic over the tunnel that matches its crypto access-list, so this ACL has to include the subnets behind each other PIX. Consequently, the ACL's on the 3000 have to include all of these networks as the local network.
This is quite easy to do if you set up your spoke networks correctly. A good way to do this is make sure each spoke subnet is say, a subnet of 10.0.0.0/8. So spoke A is 10.1.1.0/24, spoke B is 10.2.2.0/24, spoke C is 10.3.3.0/24, etc.
Then your PIX ACL for spoke A just has to be:
access-list ipsec permit ip 10.1.1.0 255.255.255.0 10.0.0.0 255.0.0.0
PIX ACL for spoke B just has to be:
access-list ipsec permit ip 10.2.2.0 255.255.255.0 10.0.0.0 255.0.0.0
You then just have the reverse on the 3000 and everything get's routed accordingly.
