rapture - a phenomenon for which I have observed no existing name in which the President strategically appoints legislative opponents to desirable Cabinet positions.

Rapture works owing to an amendment and a convention: the amendment holds that the Governor of each state may be invested with the power to temporarily fill vacancies until the term ends and/or the seat can be filled permanently by special election - usually during the next biennial election, although there are exceptions to this. The state legislature has the power to regulate this locally. In three cases - AK, MA, and AZ - the governor has no such power and the election is to occur within a set period

The convention is that the Governor is anticipated to appoint acting senators by party. This means that there is no obligation on anyone’s part to elect a Senator from the same party as the preceding, although it is not particularly common for Senators who were elected comfortably to see the seat’s party change permanently after their absention.

See a map of potential raptures (Dem and GOP) here.

Assuming a Democratic administration (the alternative would require an unimaginable succession of deaths at this point), the following Republican Senators are eligible for rapture (colors indicate Presidential vote, and italics indicate leaders, whips, chairmen, or other essentially unrapturable senators)

Arizona has two GOP senators - John McCain and Jon Kyl - but appointments result in special elections immediately rather than following an appointment, making rapture impractical.
Iowa - Chuck Grassley.
Kansas - Pat Roberts; Sam Brownback.
Kentucky - Jim Bunning; Mitch McConnell.
Missouri - Kit Bond.
Maine - Olympia Snowe; Susan Collins.
North Carolina - Richard Burr.
New Hampshire - Judd Gregg.
Ohio - George Voinovich.
Oklahoma - Jim Inhofe; Tom Coburn.
Pennsylvania - Arlen Specter.
Tennessee - Lamar Alexander; Bob Corker.
Wyoming - Mike Enzi; John Barrasso.

In addition, several Democratic senators in states with Republican governors - Daniels Inouye and Akaka of HI and Senator Feinstein of CA - are old enough that there might be reasonable worry their seats will be lost to the GOP. This is especially true of the two older senators, both WWII veterans (and incidentally Asian-Americans, the former a Nisei and the latter a Hawaiian-born Chinese-American) whose replacements would be Republicans facing a relatively weak local Democratic party and historically low turnout for reelection.

Some of these raptures would be politically sound. (Grassley has been suggested repeatedly for Agriculture, for instance.) Others would be inconcievable - both Senators from Oklahoma have little experience outside of right-wing kulturkampf, and with the GOP in shambles it seems like a serious risk that even a fairly low-profile Senator might use the Cabinet as a springboard to an effective 2012 run.