The headline in the Washington Post piece says "Lobbyists Feel the Pinch As Downturn Hits K Street".

If you read the article there is certainly evidence of a tail-off in the amount corporations spend trying to directly lobby congressional representatives.

But as the article points out, it may not be so much a reduction in spending as a redirection of spending to activities that are less public, less accountable and often frankly less honest:

Lobbying insiders say factors other than the economy are driving down the numbers. Trade groups and private corporations, for example, increasingly are pouring resources into television ads, grass-roots organizing and other advocacy efforts not counted under the narrow definition of lobbying required for House and Senate disclosure forms.

Whereas the article points to the defense industry as an example of one that is spending less because of the downturn, an unrelated New York Times article seems to suggest a different reason:

Despite a recession that knocked down global arms sales last year, the United States expanded its role as the world’s leading weapons supplier, increasing its share to more than two-thirds of all foreign armaments deals, according to a new Congressional study.

The United States signed weapons agreements valued at $37.8 billion in 2008, or 68.4 percent of all business in the global arms bazaar, up significantly from American sales of $25.4 billion the year before.

Not so much a downturn in lobbying expenditure, then, as a redirection to politically friendlier places elsewhere?