Psalm 109:8 and Obama

Bumper stickers and T-shirts have appeared for sale online with "Pray for Obama" slogans accompanied by quotes from Psalm 109:

May his days be few; may another take his place of leadership.

So, they're praying for Obama's tenure to be a short one. But what does that really mean?
A clue may be in the verses of the 109th Psalm that follow verse 8:

May his children be fatherless and his wife a widow.
May his children be wandering beggars; may they be driven from their ruined homes.
May a creditor seize all he has; may strangers plunder the fruits of his labor.
May no one extend kindness to him or take pity on his fatherless children.
May his descendants be cut off, their names blotted out from the next generation.
May the iniquity of his fathers be remembered before the Lord; may the sin of his mother never be blotted out.
May their sins always remain before the Lord, that he may cut off the memory of them from the earth.

The slogan comes at a time of heightened concern about anti-government anger. Earlier this year, the president's senior adviser, David Axelrod, said that Tea Parties could lead to something unhealthy. In September, authorities shut down a poll on Facebook asking if President Obama should be killed. Still, that doesn't push the Psalms citation into the realm of hate speech, says Chris Hansen, a staff attorney with the American Civil Liberties Union (ACLU).
The use of Psalm 109:8 is ambiguous as to whether its users are calling for the President to serve "only one term, or less than one term," he says.