Is Japan's technology compatible in America?

Not a good idea.First off, you will probably be paying more for them in Japan.There's the matter of a warranty as well.It may be void outside of Japan.The "cool gadgets" will have instructions in Japanese....

gadgets like iPods, laptops, cameras, etc will work fine. You just need to get an adapter for the charger. Some chargers are shaped differently and will not fit into the electric outlets in North America; and if they do, you wouldn't want to as the device is designed for Japanese/Asian electric voltages.

In regards to cell phones, you need to make sure you're getting the GSM or ones that accept sim cards. Japan is on the CDMA bandwidth and their phones are made accordingly. These phones will not work in North America.

If you are from the US, the voltage of Japanese electronics is slightly different from American, but close enough that you can plug a Japanese DS or camera into a wall outlet in the US and have it work just fine.
Most gadgets should work, but the menus will be all in Japanese. You should also keep in mind that many gadgets (particularly fashionable branded products like iPods) are considerably more expensive than in the US!

Unfortunately, Japanese cell phones will not work in other countries.