When it comes to benchmarking the card I compared the Kingston SDC/1GB-2ADP microSD card to the Sandisk 128mb SD card I have. Since it is hard to benchmark these cards in a phone or MP3 player; I used the card reader in my Dell Inspiron 9400 laptop with a Core Duo T2350 @1.86gHz to run the flash memory test found in SiSoft Sandra Lite 2007 to get read and write performance numbers.
As you can see from the charts the Kingston card was fast when it came to the read test. As the files size got bigger that is where the increased read speed was noticed, on average 20% faster than the SanDisk card.
For the write test the Kingston SDC/1GB-2ADP card slower in a couple of the write tests, but nothing drastically slower.