Under the Mavericks version of the Apple operating system, the Terminal session now also copies that formatting by default, when pasting you can choose to paste and match style (alt-cmd-V), but you can also disable copy/pasting the formatting from Terminal by changing the com.apple.Terminal preferences file.
Open Terminal on your Mac and enter the following command:
defaults write com.apple.Terminal CopyAttributesProfile com.apple.Terminal.no-attributes
This will strip all text attributes out of copy/pasting from Terminal