Hm, I think there will be only one Core Solo... I'd say Core Solos are processors where one of the processors is defective, so they deactivate that one. And somehow I doubt that the remaining CPU would be as good as a 2,16 GHz. Also I think it makes sense in the line up, the Core Solo is placed as the cheapest option.
I would say there will be a MacBook (no iBook anymore), following the iBook, and it will be a 1,66 GHz Core Solo in the basic version and 1,66 GHz Core Duo as an option.
The 17" MacBook Pro would have a 2 GHz at minimum and a 2,16 GHz at max., the 12" one will have the low voltage ones, 1.5 for basic version, better one 1,66 GHz. Maybe make low voltage an option on MacBook and MacBook Pro 15".
I'd say that Apple would like to differenciate between MacBook and MacBook Pro, also in CPU speed. I don't think the Core Solo would be much slower than the Core Duo, I'd say for the cheapest box its ok to use the slowest CPU.
And the Mac Mini... as much as I would love to see a 2,16 GHz Core Duo in it...

2 variants: Core Solo 1,66 for the basic version, Core Duo 1,66 for the better one. But that also depends on the jobs it will have to do... maybe it will require a more powerful CPU.
Btw.: Sure the people were expecting Pentium Ms for the MacBook Pro? It was well known that Intels dualcore Pentium M follow up codenamed Yonah was expected for the beginning of the new year. I'd say at least it has been expected to have a Yonah, if not its follow up.