I, for one, cannot wait for this. I recently purchased Office 2008 for Mac not long after they announced the free upgrade offer, simply because the Apple iWork suite on the iPad is getting more attention than the Mac itself, which is really sad.
After using OFM for a week it was clear to see that Office is still leaps ahead of iWork. I hope 2011 is a worthwhile upgrade, although I'm a little disappointed that I'm going to have to pay for an upgrade to get Outlook, especially after they've removed Entourage (which is included in the lowest 2008 edition.)
Also there's an error in the article, 2nd paragraph - "...with anyone buying the 2009 version between now and then..." - it's actually 2008, not 2009.