Although it would have been smarter to wait until he had the nomination before comparing himself to Reagan (Memo to Barack: Dutch is not exactly the most popular figure with the base of the party whose nomination you're trying to win), there is something shrewd in a liberal Democrat attempting to coopt the legacy of the 40th President. After all, it's exactly what Reagan did with FDR and JFK in 1980 and 1984, and what FDR did to his Uncle Theodore in 1932: take the most popular political figure in the other party, now safely deceased, and associate your agenda with their accomplishments, thereby marginalizing the current holders of that partisan legacy.
We tend to forget that neither FDR in 1932 nor Reagan in 1980 ran particularly polarizing races. Both men attempted to appeal across party lines, with the advantage of knowing that their races were basically referenda on the incumbents, and it was left to their opponents (Hoover and Carter) to get the country to fill-in-the-blanks as to what they really intended to do. Reagan spent almost the entire period after the 1980 GOP Convention denying he was going to gut Social Security, or rape the environment, and was on the defensive so much of the time that Carter actually had a small lead in some polls going into the one Presidential debate one week before the election. In fact, his famous line, "there you go again," was made in response to an altogether accurate charge by President Carter that he would try to cut Medicare if he was elected.
By presenting a moderate image, masking some of the less popular aspects of his ideology, and by campaigning as the true heir to FDR and the New Deal, Reagan was able to pull away from Carter and win a decisive victory. Although much has been made, by Prof. Krugman and others, of Reagan's clumsy attempt to pander to Southern whites, he won the Presidency not through a "Southern Strategy," since the South was Jimmy Carter's strongest region in that election, but by pursuing votes in every region of the country tired of the perceived ineptitude of the Carter Administration. Similarly, FDR succeeded not by polarizing the electorate in 1932, but by going after anti-Hoover votes everywhere in the country. It was by winning decisively, not by seeking vengeance for past political defeats, that gave them their mandates.
I just wish the junior Senator from Illinois had waited 'til there were actually votes to be had by appealing to the Reagan Legacy. I don't think it's such a fruitful strategy in Democratic primaries to be kissing the ass of the late Ronald Reagan. It also grants an invitation to people like Prof. Krugman to mischaracterize his statements (like he did last month with FDR). There aren't enough open primaries and caucuses left.
[UPDATE (1/18)]: Here's a good piece on Reagan's true legacy, which punctures the myth that Reagan was even a particularly popular President. True, as far as it goes, but it really misses the point about the savvy involved in coopting the GOP's most beloved icon for progressive purposes.