Before folks start cold voting because its expensive for an SDHC, please note that the read/write speeds are blazingly fast for these and as such suited for DSLRs and the like. Please see the following link:
I needed one for my Pentax K-M as it only accepts SD/SDHC and this is the best price/GB for the extreme cards.
As an interesting point, the "Class No." classification system is not as obvious as it looks. The classes range from 2, 4 and 6. At class 6, it means that the card can perform writes at 6mbs, class 4 at 4mbs etc. Cards such as the Ultra series (15mbs) and Extreme (30mbs) can write a lot faster but it isn't defined within the classification. As such, cheaper cards can rightly claim Class 6, reading at 6mbs but not necessarily 30ms like this one :)
Hope this helps someone.