The Details
The Celeron 366 we received is an engineering sample, usually sent to motherboard manufacturers. The plastic PGA package surrounding the chip is exactly the same size as that of a Pentium MMX, but with a higher pin density and layout. The Celeron 366 runs on a standard 66Mhz bus at a 5.5x multiplier.

On the left, the Socket-7 K6-2
On the right, the Celeron 366
The Celeron 366, like the 300A and 333, features 32k of on-die L1 cache (16k data, 16k instruction), and 128k of full processor-speed on-die L2 cache. Having on-die L2 cache places the Celeron in line with the new iteration of AMD processor, the K6-3, which has 256k of on-die L2. Both of these CPUs are more advanced than the Pentium II processor in this regard, which typically has more cache (512k) that runs at half of the processor's core speed.
We were able to abscond with two motherboards for our tests, the Supermicro 370SBA, based on the Intel 440BX chipset, and the Tekram S3AP-A, running the Via Apollo Pro+ AGPset.

The Socket-370 SuperMicro 370SBA
The SuperMirco 370SBA resembles a typical BX board, sans Slot-1 connector. It contains 1 AGP slot, 4 PCI slots, and 3 ISA slots. It has a standard ATX mounted IO with 2 serial, 1 parallel, 2 USB, and PS/2 keyboard and mouse connectors. Its 3 DIMM sockets can accommodate up to 384MB of EDO or unbuffered 3.3v PC-66 or PC-100 SDRAM DIMMs, or 768MB of registered SDRAM. Rounding out the count are the standard 2 PCI EIDE and 1 floppy port.