As said above-if the nano is updated, it will be in i the next month or so...I don't see a need to rush out and buy one because I'm very certain that Apple won't discontinue the nano yet...they need to hold onto a music only player that isn't the shuffle for a little longer...
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Or if u do worry that it might be discontinued...u could go buy one a few days before apples event and take it back and exchange it if a new one comes out...just dont open it until u are certain