The version of Internet Explorer in Windows Vista has a new name. According to Microsoft’s IE Blog:
With the release of Windows Vista Beta 2, I want to announce that we will be naming the version of IE7 in Windows Vista “Internet Explorer 7+”. While all versions of IE7 are built from the same code base, there are some important differences in IE7+, most significantly the addition of Windows Vista-only features like Protected Mode, Parental Controls, and improved Network Diagnostics. These features take advantage of big changes in Windows Vista and weren’t practical to bring downlevel. The IE7+ naming gives us an easy way to refer to this version. (“The version of IE7 in Vista” doesn’t roll off the tongue as easily…)
It also has the marketing side-effect of making the version of IE7 in XP the equivalent of IE7–minus.

My problem with the new name is that a reasonable nontechnical observer running Windows XP will hear about it and think that the “plus” part is an add-on that they should be entitled to as well. Given that the changes relate to features in the OS, I would have preferred a naming convention that reflects that reality: IE7/XP and IE7/Vista.
But nobody asked me.
Ed,
I see your point but I still think naming the Vista version differently is a good idea since it will offer added security functionality not found in the XP version. It comes down to how though. Maybe IE 7.1?