From this:

A federal appeals court panel ruled Tuesday that a portion of Oklahoma’s anti-illegal immigration law is enforceable now, while other provisions of the law are not.

In a divided opinion, a three-judge panel of the 10th U.S. Circuit Court of Appeals in Denver said that though the plaintiffs would likely triumph with most of their claims, Oklahoma can force employers to check employees names against a federal database of workers eligible to work in this country...

...Saying the provisions are likely to be held unconstitutional, the panel unanimously upheld the preliminary court orders barring enforcement of these provisions:

*A prohibition against firing workers legally in the country while retaining workers illegally in the country.

*A requirement that businesses working with private contractors obtain documentation that workers are legal or, without documentation, withhold taxes at the top rate.

The lead organization involved on the pro-illegal immigration side is the US Chamber of Commerce, with other chambers and business groups also involved. Oklahoma can ask for a full appeal or can take it to the US Supreme Court. Greg Siskind says (link):

"This is a major blow to legislators around the country that have been trying to pass state laws regulating immigration... This presumably puts many laws around the country in jeopardy."