Just test the thing and get on with it.
Microsoft's Mike Nash has just stated that, although April 11's patch to IE will include the updated behaviour change made necessary by the Eolas lawsuit, because people outside of Microsoft are concerned that they haven't had a chance to test it enough on their LOB (line-of-business) applications, there will be an option to disable the behaviour change.
Message to corporate America:
Would you just test the thing and get on with it, please?
The behaviour change is simple, and has relatively minor effects. It's irritating chiefly in that it is a) so unnecessary, and b) more awkward and counter-intuitive than the behaviour Eolas claims is "non-obvious" and therefore patentable (leaving aside the issue of prior art).
And for those looking for explanations of why Microsoft is choosing to code around the feature that Eolas' patent obscures, I'd point to recent patent cases such as the Blackberry / NTP settlement, where (I'm paraphrasing, I apologise if I get the legal terminology wrong) even after the USPTO said that NTP's patent was invalid and would be revoked, the judge in the case ruled that NTP's patent needed to be upheld, and that Blackberry (RIM, actually) should either settle with NTP to NTP's tune, or turn off their service.
So, even if Microsoft believes they'll win in the Eolas patent suit, they have to do what they can to lessen the intervening damage.