Best device to work out with/protect from moisture?

I'm considering getting an iPod Shuffle as a cycling and workout music device. However, I could also use my existing iPhone, but would need a new case to secure it to my body.

Two questions:

How is the Shuffle for dealing with moisture (ie sweat)?

Can anyone recommend an armband case for iPhone 4 that will protect it from excessive body heat and moisture?

Thanks.

iPod

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