In an entry on the IE team's blog, group product manager Tony Chor said that the new moniker would denote the Vista-only features in that OS's browser -- protected mode, parental controls, and better network diagnostics -- all of which are missing from the Windows XP version.
The two IE editions share the same code base, and except for the three Vista-specific features, are identical.
Beta 2 of both the XP and Vista versions are currently available, but the second beta for Vista won't be open to all users for several weeks, said Chor. At the moment, IE 7+ Beta 2 can be downloaded only by Vista beta testers.
User comments posted to the blog were generally unkind to the name.
"This is nuts, you will cause more confusion with this than leaving it as IE7," wrote a user identified only as "Steve."
"I was going to say that this was a 'poor' naming decision but after about, oh, 5 seconds of thought I decided not to mince words: this is a STUPID decision, for the very reasons mentioned by other posters here," a user named "Cal Jacobson" added. "The 'plus' is merely to give the illusion that one version of IE is better than another -- thus another reason for users to upgrade to Vista."
Chor said that information about the timing of the at-large Beta 2 of IE 7+ will be posted on the blog "shortly."