Read the fine print though -- it seems like the 3G access can only be used for books outside of US (I checked UK and Denmark, and both say "Blogs and the experimental web browser are currently not available for your country"). Not sure about e.g. Wikipedia.
Also "Service fees for transferring personal documents via Whispernet are currently $.99 per megabyte." -- but I think that might already be the case for the US Kindle. That's similar to the fee I pay for basic wireless data service.
"Kindle (U.S. Wireless) user: We'll send personal documents to your Kindle via Whispernet while inside the U.S. wireless coverage area for a fee of $.15 per megabyte.
Kindle (U.S. & International Wireless) user living in the United States: If you transfer personal documents to your Kindle via Whispernet while inside the United States, the fee is $ .15 per megabyte. When travelling outside the United States, a fee of $.99 per megabyte will apply.
Kindle (U.S. & International Wireless) user living outside the United States: We'll send personal files to your Kindle via Whispernet for a fee of $ .99 (USD) per megabyte anywhere in the world you access Whispernet service."
Also "Service fees for transferring personal documents via Whispernet are currently $.99 per megabyte." -- but I think that might already be the case for the US Kindle. That's similar to the fee I pay for basic wireless data service.