As the other reviewer has said, xD cards can be picked up for a few pounds but I too wasn't willing to take the chance on receiving something manufactured in somebody's shed. I paid extra for this Olympus card, one reason being that the CF card I use doesn't allow for 'Panoramic' photos and it's something I wanted to try.
I don't know the transfer speed of this card, but as those things are measured in fractions of seconds, I doubt I'd notice anyway. (Is there really a discernible difference between 90mb/s and 50mb/s?) Its capacity that counts and this allowed me 120 photos in RAW but nearly 6000 in Small Normal (both similar amounts to my 2GB Compact Flash).
The card also comes with a 20-digit serial number that has to be entered to activate the ART and 3D functions within the Olympus Master software. This number was on a piece of paper tucked in the back of the cardboard pack the card arrived in and as it's an official Olympus card, I guess they're all packaged that way. It could quite easily be thrown out by mistake. The two-year warranty helps, too. Okay, it may cost more but you'll know it will work; if by chance it doesn't, it will be sorted out, which is slightly better than hearing, "It's yours now, mate."