USCD panel of legal professors state that SB 1070 probably passes Constitutional muster.

Leslie Berestein of the San Diego Tribune reported on May 14th that a panel of three law professors discussing Arizona law SB 1070 could well pass constitutional muster, although violations could occur during enforcement. 

The article is here.

The primary points made by the professors were:
1) It does not appear to give law enforcement more authority, contrary to claims by opponents of the law.
2) The the law was carefully written by Russel Pearce with the help of Constitutional law professor Kris Kobach of the Univ. of Missouri. It mirrors federal immigration laws. Because immigration law is adjudicated  by the federal government, the Arizona law could be pre-empted because federal law overrides state law. Arizona is essentially notifying the federal government that it will enforce the law until the federal government explicitly orders them to stop doing so. Since there is no conflict, the likelihood that the federal government will "pre-empt" the enforcement of this law is unlikely.  Further, if SB 1070 is found fail constitutional muster, that means that federal law ALSO fails constitutional muster, an unsavory consequence for the federal government.