Are there any new, improved ipod touch-like devices by apple coming out soon?

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I'd like to buy an Ipod touch or Iphone, but I'm wondering if I should wait in case an improved similar device comes out soon. Do you know if apple has any plans to release anything new in the next year or so?
Is there any chance they will come out with an Ipod Touch that has upgrades such as the microphone built in(like the Iphone) soon?
Thanks!