I don't have specific numbers at the top of my head since I usually shop on base, but it definitely is more expensive here for nearly everything. Okinawa is one thing, but Tokyo is even worse.
Now, that being said, there are instances when Japan is cheaper. A higher dollar rate helps a great deal, but I'm not sure if it will head back to 130 like it was when I arrived. It would be nice for big ticket items (it was apparently 145 last year -- holy crap!). Checking prices on electronics here and looking online, the top of the line items, like plasma TVs, are cheaper here by about 10-30% (hard to tell because the models aren't the same). Unlike what's stated above, voltage isn't always an issue because many of their electronics are automatic voltage for usage here in Japan, in Europe, or in the States. I think but have not confirmed that all their TVs are that way. In short, the savings is only on the high dollar stuff, but it can be pretty substantial (probably due to shipping costs, import tariffs or customs fees).
The voltage here is 100v versus 110v in the U.S., and we've discovered that Japanese devices will work on U.S. current without any problem (we have a Kenwood cordless phone/answering machine in our house that works just fine even though it's 100v -- our house here is wired for American voltage). We were told that there also is a trend to start building homes with American current, at least here in Okinawa, because they have discovered that it's more efficient than what they use now. Our Japanese housing agency told us that. We'll see about that.
Laptops seem fairly expensive because they mostly have Japanese brands, Sony and Fujitsu. Great gear but pricey. I haven't looked at them in great detail though.
If we head to the store this weekend, I'll see if I can grab some prices.
As for the apple comment, the local fruit and vegetable markets aren't expensive at all. If you're trying to eat like an American, it will be expensive. If you try to eat like a Japense person, it isn't bad at all. Again, though, we nearly always shop on base since it's just easier in so many ways.