Today hackers released a file containing 453,000 email addresses and passwords taken from the Yahoo Voices service. The passwords were not encrypted and the list is now widely available on the Internet.
Change your Yahoo password NOW.
Reports indicate the password leak is contained to the Yahoo Voices service. Even if you did not use this service we recommend changing all Yahoo related passwords.
If you used the same email address and password combination for other online services, change those passwords NOW. Criminals know people tend to reuse email addresses and passwords for multiple accounts and will try to exploit this knowledge to gain access to other online services.
NOTE: Not all passwords leaked are for yahoo.com email addresses (From Tech Crunch):
It notes that 135,599 emails came from yahoo.com; but that a further 106,185 came from gmail.com; 54,393 from hotmail.com; 24,677 from aol.com; 8,422 from comcast.net and 6,282 msn.com.