We have recieved information that the SN78SH7 is due for release towards the end of June, it will include the following features:
Support for AM2+ Phenom Multi-core Processors w/HyperTransport 3.0 Technology.
Onboard HDMI Port
Dolby Digital Live & DTS Connect 7.1 Surround Sound
8 series graphics (so you get DirectX 10 Support)
All solid capacitors
Gigabit Lan
eSATA
So pretty decent specification although I wonder if it will ship with a higher PSU than the 300W model. The H7 chassis is slightly bigger than a G5 but is not as big as a P chassis. I'll post more info when we hear more ourselves.