The new non-all-in-one lineup this fall will be:
MiniMacIntel:
Tiny, one Yonah/Merom dual core, extremely limited expansion (one 2.5" disk, 2 GiB RAM max, integrated graphics, no slots)
New Conroe Mini-Tower:
Mini-tower (or pizza box - think the size and shape of a home DVD or stereo component), one Conroe dual core, max 8 GiB RAM in four DDR2 DIMMs, integrated graphics *and* PCIe x16 slot for graphic card, one or two 3.5" disks (up to 1500 GB disk), one or two optical, two PCIe x4 slots for other cards (like TV tuner)
Mac Pro (PowerMac replacement):
Maxi-tower, dual Woodcrest dual core, max 16 GiB to 64 GiB RAM, PCIe graphics card + more slots, probably more disks than the PMG5
Several strong reasons for the new Mini-Tower:
- Xeon (Woodcrest) CPUs and chipsets are much more expensive than the Core 2 Duo (Conroe) parts, so an all Woodcrest tower lineup would be quite expensive
- There's already a huge gap between the Mini and the Maxi PMG5 (in size and price)
- Apple will introduce an HTPC system, and those are often in home-stereo form factors
- Everyone else will have $800 to $1100 Conroe dual-core mini-towers, Apple needs something to compete in that price/feature range (Mini and iMac don't)