Congress wants to pass a bill that would put serious fines (10K for bitcoins in opposed to 5K for cash, IIRC) and jail time (ten years, in opposed to five IIRC) if you cross the border without reporting your bitcoins (in addition to confiscating your bitcoins of course).
http://www.coindesk.com/forfeit-bitcoin-congressional-bill-draws-fire-border-check-rules/ [coindesk.com]