No joke.

House Joint Resolution 1089 (PDF)

Oklahoma House of Representatives Roll Call (Voted 92-3-6 in favor.)

Oklahoma Legislature Bill Search (Type in 'HJR1089' for more details)

And to quote the resolution in its entirety;

STATE OF OKLAHOMA
2nd Session of the 51st Legislature (2008)
HOUSE JOINT RESOLUTION 1089 By: Key

AS INTRODUCED
A Joint Resolution claiming sovereignty under the Tenth Amendment to the Constitution of the United
States over certain powers; serving notice to the federal government to cease and desist certain
mandates; and directing distribution.
WHEREAS, the Tenth Amendment to the Constitution of the United States reads as follows:
"The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to
the States respectively, or to the people."; and
WHEREAS, the Tenth Amendment defines the total scope of federal power as being that specifically granted by the Constitution of the
United States and no more; and
WHEREAS, the scope of power defined by the Tenth Amendment means that the federal government was created by the states specifically
to be an agent of the states; and
WHEREAS, today, in 2008, the states are demonstrably treated as agents of the federal government; and
WHEREAS, many federal mandates are directly in violation of the Tenth Amendment to the Constitution of the United States; and
WHEREAS, the United States Supreme Court has ruled in New York v. United States, 112 S. Ct. 2408 (1992), that Congress may not
simply commandeer the legislative and regulatory processes of the states; and
WHEREAS, a number of proposals from previous administrations and some now pending from the present administration and from Congress
may further violate the Constitution of the United States.

NOW, THEREFORE, BE IT RESOLVED BY THE HOUSE OF REPRESENTATIVES
AND THE SENATE OF THE 2ND SESSION OF THE 51ST OKLAHOMA LEGISLATURE:
THAT the State of Oklahoma hereby claims sovereignty under the Tenth Amendment to the Constitution of the United States over all
powers not otherwise enumerated and granted to the federal government by the Constitution of the United States.
THAT this serve as Notice and Demand to the federal government, as our agent, to cease and desist, effective immediately, mandates
that are beyond the scope of these constitutionally delegated powers.
THAT a copy of this resolution be distributed to the President of the United States, the President of the United States Senate, the
Speaker of the United States House of Representatives, the Speaker of the House and the President of the Senate of each state's
legislature of the United States of America, and each member of the Oklahoma Congressional Delegation.

And no, this does not mean Oklahoma is seceding from the United States. Consider this a phone call telling the loud, obnoxious neighbor to keep it down (aka, the federal government keeping to its specifically-designated powers and butting out of all other affairs).

If you can't tell, I'm excited by this.

EDIT: And it seems my excitement's a bit unwarranted, given that this was introduced on March 13th in the House, got to the Senate, then was referred to the Senate Rules Committee on March 25th where it seems to have stalled and become dormant. Bleh.