I don't think many are PC based at the moment.

boards
stern
spooky
skitbpinball - pretty sure predator are going boards (started as p-roc)
PPS
Homepin

PC
JJP
P3

Unknown
dutch pinball - started out with a proc system but think I read somewhere they are going boards
Heighway - ????

Heighway did a machine called Bacardi with a limited batch of 250 units, don't know much more. They are looking at a Aus Distributor and pricing is out and reduced a little since early release figures.