This is the sweet spot at the moment for speed/price/capacity.
Other 8gb Class 6 SDHC cards seem to cost at least £13 delivered. The Kingston branded from mymemory.co.uk may be the best choice for those who like a familiar brand (£13)
mymemory.co.uk has a 16gb class 6 for £20, while the same play.com branded 16gb class 6 card is a pricy £30 (although the Class 4 card for £16.99 looks like a bargain too!)
Looks like better value than the Sandisk Extreme III 4gb SDHC for £12.50, or the 8gb for £32.99.