Images and dpi

[Vonagut]

Reading leehack's great tutorial about managing images has left me with one more question...

What dpi are product images saved at ususaly?

As I'm saving my images at 150x225 I would have thought 300dpi, but I've noticed a lot of sites using 72dpi on their thumbnails.

It obviously depends on the resulting quality. What do others do?

[Duncan Rounding]

For web purposes use 72 dpi. For printing then you would usually need 300dpi.