I'll give Sony some credit..

[bfitzgerald]

At least they had the brains and sense to use SD and MS, rather than their own memory format.
Clearly this signals that someone is earning their pay cheque, even if they made a style of camera that does not appeal to me.

[Greg Beetham]

Well, MS is their own memory format actually, there isn't actually anything wrong with MS per se except that it was not adopted widely in the industry, maybe Sony wanted to charge too much, who knows, there was a lot of collaboration with Sandisk in the development of MS Pro and Duo etc...apparently. The reason why Minolta chose CF for their DSLR cameras (so I've read elsewhere) was at the time it had one of the highest write speeds around...not sure how it compares now though with SD and MS etc.
Greg

[KevinBarrett]

Sometimes I wonder if they offer the MS slot in order to sell cards or sell cameras. If the MS memory format were significantly more competitive than SD, either in price, speed, or reliability, then they might be an exclusive advantage of the Sony system. Thus, the format would contribute to selling the cameras.

Certainly, however, it is an advantage for the new cameras that they can hold two cards and switch between them easily--in this case the cameras sell the format.