I will, however, admit that the researchers should have noted the issues with the tree-ring data in question.
Good thing they did, then. Only ten years ago, mind you.
Seriously, this whole "climategate" debacle tends to run like this:
1- Deniers exhume some e-mail / piece of code which they don't understand, but assume is definite proof of evil scheming on the part of the great academic conspiracy ("Trick!" "Hide the decline!" OMGconspiracy send teh copz!!) .
2- Scientists post explanation, showing the deniers' allegations to be baseless (The "hidden" decline in tree ring growth was published a decade ago - see Nature link above; in this very publication, it was shown to diverge from the actual instrumental record after 1960; so for the post-1960 period we basically replace tree rings with the actual instrumental data, because we trust thermometers more than tree rings when the two fail to agree; we cited the relevant articles in the caption for the graph just to be sure).
3- Deniers completely ignore scientists' explanation, and keep fantasising about their glorious victory over evil scheming scientists. See GP for an illustration.
Rinse. Repeat.
To GP and all the folks who keep harping about this "VERY ARTIFICIAL" correction code: the code in question is a one-time code for temporarily re-calibrating the tree ring data. The reason, and the coefficients, are ultimately derived from the Nature article I linked to above. For an interesting hypothesis concerning the source of this code, see comment #147 and linked manuscript on this thread.