I recently bought a Kindle and wanted the extra storage space for books. The Kindle manual states that is uses SD cards, but didn't specify if it could use SDHC cards too.
After chatting with a few people in the Kindle Discussion room, I found that others are succesfully using SDHC cards in their Kindle's, but Amazon Kindle Tech Support told me that they will not support SDHC cards at this time, should they fail.
So being an avid reader, I took the chance and ordered the SanDisk 8GB SDHC card and it works like a champ in the Kindle. I've loaded 7 books to it already and can read and write to it without a problem. Be aware though, that only 7.3 GB of space is available on the card for storage when used in the Kindle.
I have had no problems with any of the SanDisk SD, SD Micro, or XD cards I've purchased over the years. They are reliable & durable and I will continue to purchase this brand again in the future.