Vera,
Just to clarify, are you intending to store all the campaign IDs as part of the contact record? Your contacts can be tracked by the campaign they were part of through Insight or segmentation but I don't know that you'd want to keep the campaign ID as part of a contact record. If you still feel it is necessary, you might want to use a custom data object to store that rather than a contact field. Our SFDC update program looks to see if the contact has a contact ID not a campaign ID for creating new contacts in SFDC.