I don't know if you were just linking the Seattle article or meant to endorse it. However, I think it's easy to see a just and rational reason why Microsoft might want the bill redesigned. It calls for minimum damages of $500 per spam against individuals, and $1,000 against the Internet service provider! And it seems there's no cap.
Knowledgeable people will tell you that MSN and Hotmail and other ISPs and mail providers fight hard to prevent spammers from using their services, but there's no way to be perfect! So to open up unlimited liability at $1,000 a pop... that seems pretty crazy. Sounds like lazy legislation that regulates to punish someone wihtout doing the hard work of figuring out how to actually fix the problems. Microsoft's proposed changes (surprise!) were aimed at reining in the overzealous regulation to be less of a ticking time bomb for ISPs.
I don't know what Unspam is reporting on. I assume they're worrying about different problems. But the Washington State spam laws seem worth lobbying against...
According to Michigan Legislature, the bill in question has passed the Senate and is currently mired in a House committee. It's been there since June for whatever reason, at least if this information is current.
In response to the previous comment, I see NO reason that ISPs shouldn't be held accountable for their own systems. Sure, the Big Three have a stake in killing bills that could lead to lawsuits against them, but that only makes it more important to pass those bills. People are abusing Hotmail, Yahoo, etc. to send spam, and none of those service providers are doing anything about that. They're instead opting to sue the people doing it and kill potential laws that make them stop ALLOWING it. I say pass the bills and kick MSN, Yahoo, and AOL in gear to fix the problem of allowing the abuse in the first place. They half-assedly treat symptoms (spam filtering, lawsuits, etc), they've done nothing to prevent the illness. Kinda like a certain world leader I could mention.