Today the state legislature passed a civil unions bill (full text here), granting same- and opposite-sex partners all of the legal rights, obligations, and privileges of spouses under state law. The vote was 32-24 in the state senate today, following approval in the state house yesterday. The governor will sign the bill.
There are a couple of noteworthy provisions in the bill. First, the new status is available to opposite-sex spouses who choose not to marry. This makes the Illinois law different from other civil-union laws, like the ones in California, Oregon, and New Jersey, which generally make the equivalent status available only to same-sex couples on the theory that opposite-sex couples can marry. (California has a limited exception for opposite-sex partners when one is at least 62 and eligible for Social Security benefits.)
Second, the bill contains a “reciprocity” provision requring the state to recognize out-of-state same-sex marriages or civil unions.
Illinois came a little later to same-sex partnership recognition than I expected, but it now joins a large state population to the one-quarter or so of all Americans living in a jurisdiction with same-sex marriage or its equivalent.