Sometime this week – possibly even today — Illinois may make history by passing a civil unions law that will grant same sex couples all the rights of marriage except one: the ability to call their union what it really is.

Governor Pat Quinn favors same sex marriage but backs civil unions as what’s possible.

And that seems to be the bottom line: in the year 2010, in the land of Lincoln, civil unions are all same sex couples are going to get: some kinda legal.

“Right now, it looks very good,” says Greg Harris, 13th district state representative and the law’s principal and most dogged sponsor. “Would I like to see same sex marriage? Yes, of course, but as you look through the struggles of every movement, you’ll see that everything is done in steps. Civil unions is a step.”

The law will entitle same sex couples to “the same legal obligations, responsibilities, protections, and benefits afforded or recognized by the law of Illinois to spouses.” The dissolution of the unions will be processed much like a civil divorce.

“Right now Illinois doesn’t recognize same sex couples at all,” says Christopher Clark, senior staff attorney for Lambda Legal’s Midwest office. “It’s best to get some protections now instead of god knows when. People can’t wait for the political climate to be right for same sex marriage. This will provide rights and benefits people need right now.”

But don’t be fooled: Though the language is virtually identical, though the rights are essentially the same, civil unions do not share the same status as marriage.

“There are differences,” says Craft. “Independent commissions have found that civil unions don’t necessarily provide equal treatment. Even though the law provides the same rights, the actual reality is that folks in civil unions are still discriminated.”

In other words, that old canard of separate but “equal.”

(In fact, even in states where same sex marriage is legal, the federal Defense of Marriage Act makes them ineligible for more than a thousand different federal benefits of which heterosexual married couples in the U.S. may avail themselves.)

When civil unions become legal in Illinois, I will, of course, celebrate.

But forgive me if it’s bittersweet.