They say here:
http://www.altiris.com/Support/Online/ProductEOL.aspx
"To find the "Release Details" for your product, navigate to the Symantec Enterprise Support homepage and select "Supported Products A-Z.
Select your product from the list. Select "Release Details" in the "Product Support" section, which can be found on the right side of the product page.
From the "Release Details" page, use the drop down to select your product version and display that version's Release Details, including End of Engineering Support and End of Assisted Support dates."
Which gives:
"Release Date
2006-01-12
End of Engineering Support
2013-03-07 Last date for patch releases
End of Assisted Support
2014-03-07 Last date to contact support"
But don't forget that v6 solutions may go EOL earlier, Carbon Copy Solution has already gone past "End of Assisted Support"