From the SRD:
Try Again: Any conditions that apply to successive attempts to use the skill successfully. If the skill doesn’t allow you to attempt the same task more than once, or if failure carries an inherent penalty (such as with the Climb skill), you can’t take 20. If this paragraph is omitted, the skill can be retried without any inherent penalty, other than the additional time required.
Emphasis is mine. The Hide skill does not have a Try Again paragraph therefore by the rules Take 20 is allowed for Hide.
Victor Sim
Try Again: Any conditions that apply to successive attempts to use the skill successfully. If the skill doesn’t allow you to attempt the same task more than once, or if failure carries an inherent penalty (such as with the Climb skill), you can’t take 20. If this paragraph is omitted, the skill can be retried without any inherent penalty, other than the additional time required.
Emphasis is mine. The Hide skill does not have a Try Again paragraph therefore by the rules Take 20 is allowed for Hide.
Victor Sim