Lots of folks have already urged caution for business users to think twice about Firefox (myself included). This adds further fuel to the fire. At the end of the day, announcing now for a beta sometime this "summer" with no comment about features or fixes is just good old fashioned FUD, regardless of who you think the target of the FUD is.
This is one of the reasons that I’ve just downloaded Firefox: I’m fed up of waiting for Microsoft to pick up the pace of IE development. And, increasingly, Firefox offers what I want – but more of that later (really!)