Deal: Get a Personal Firewall Protector for Your Notebook for Free

Buy.com has Kensington Personal Firewall For Notebooks [Buy.com affiliate link] on sale for a listed price of $30. The product has a $20 mail-in-rebate which is valid till Friday (December 22nd) and use Google Checkout to get another $10 discount, making the final price at $0 with free shipping. According to the product description, 

• Detects and protects against hackers in all wireless environments–even outside corporate firewalls
• Hides your identity from the Internet
• Safeguards important data stored on your notebook
• Protection will not interfere with corporate firewall and anti-virus software
• Inbound/Outbound Internet Packet Filtering
• Port Scanning

Looks like a nice piece to have for free.