I've been in Spain for the past several weeks and have had no problems with 3G or with the hotel's wifi. I received the following when I first turned on the wireless in Europe:
"Important Reminder About International Delivery Fees
You can get books wirelessly in less than 60 seconds while traveling in over 100 countries. You can also stay in touch with news from home by having your newspaper, magazine, and blog subscriptions delivered wirelessly to your Kindle while you are abroad.
Additional fees apply for receiving some items using 3G wireless outside the U.S.:
For subscriptions, you can continue to receive all of your newspapers, magazines, and blogs via Whispernet 3G wireless for a weekly fee of $4.99. If you have subscriptions you will receive more details on this optional service in a separate letter on your Kindle when you travel outside the U.S.
For personal documents delivered to your Kindle via Whispernet 3G wireless while outside the U.S., the fee is $.99 per megabyte, rounded up to the next whole megabyte.
These additional fees do not apply when receiving these items via Wi-Fi. If your Kindle does not have Wi-Fi, you may also download these items to your computer at no additional charge and transfer them to your Kindle using USB.
There is no charge to use Whispernet 3G wireless outside the U.S. to receive books, receive single periodical issues, access archived items, browse the Kindle store, or use the experimental web browser."
Hope this helps!