Please be cautious of any email that asks you to update your personal or financial information. If you have ANY doubts about the validity of an email, do not respond to it and do not follow its instructions.
Here's what you could do:
1) Report it to the real company: for example, eBay's website tells you how to report a suspicious email to them, so they can assess it quickly - http://pages.ebay.com/education/spooftutorial/spoof_4.html. Check the website of the company that the email claims to be from for more details on their policies - for example, eBay has a special mailbox to receive reports from you: spoof@ebay.com
2) You can report the "phish" attempt to the Anti-Phishing Working Group http://www.antiphishing.org, which keeps an updated list of the current scams to look out for, for the benefit of all users.
Important: if you become suspicious about an email after reacting to it, please report this to your local police immediately. Please also inform the company from whom the email is claimed to be from.