Summary form only given. We present APENet, a new high speed, low latency, 3-dimensional interconnect architecture optimized for PC clusters running LQCD-like numerical applications. The hardware implementation is based on a single PCI-X 133MHz network interface card hosting six independent bidirectional channels with a peak bandwidth of 676 MB/s each direction and measured latency less than 10 /spl mu/s. The internal packet switching capabilities of the network card allows up to three couple of links simultaneously active. The current software environment, based on Linux, is made of a low-level library and a high-level application library. An MPI implementation and a network device driver are being actively developed.