There you are. Now it appears that indeed there is a company policy violated. Please bear in mind that an employer is free to regulate, according to his own discretion and judgment, all aspects of employment, including hiring, work assignments, working methods, time, place and manner of work, tools to be used. Processes to be followed, supervision of workers, working regulations, transfer of employees, work supervision, layoff of workers and the discipline, dismissal and recall of workers.
Usually, when an employer states a policy regarding any issue in the workplace, including privacy issues, that policy is legally binding. Policies can be communicated in various ways: through employee handbooks, via memos, and in union contracts. Accordingly, the restriction embodied in your handbook is justified.
Be that as it may, the core issue now boils down into the reasonableness of the duration of the confiscation. I agree with Sir attyLLL that 1 to 3 days is sensible. Problem is they don't know how to check the data in your ipod thus they wanted you check it yourself so it might take a little bit longer. I suggest you comply to their directive.
However, i am quite disturbed with their request that all data in your ipod be likewise deleted even if they will not found any company data inside it. That's already going overboard! I suggest you object to it.
Regarding the cellphones, you should be grateful that at least these gadgets are allowed.