Denise Ho, a Microsoft product manager working on the MSN Search Toolbar, has this update on tabs:
Our goal in delivering this feature was to give IE users a tabbed browsing solution to enhance overall online search and browse experiences prior to the official release of IE7 without them having to install a completely new browser.
Many of you have reported a flicker when you switch tabs. We understand that this is bothersome and are actively working on improvements to reduce the tab flicker. There have also been reports of issues associated with tabs and using F11 in IE to get to full screen mode. We are also looking into a fix for this.
Give MSN credit for linking to at least five posts criticizing the performance and implementation of the tabbed browsing feature in the latest MSN Desktop Search toolbar (including mine, but not this one, to no one’s surprise). An improved version of the toolbar should be available soon, they promise.
Ed Bott 
Your link to your post is broken… you accidently put in some of the sentence from the website into the HREF tag.
Thanks, Wes! It’s fixed now.
Stop being so forgiving.
Mistakes from companies, esp megacorps, should be treated with the derision they deserve. They made be made up of individuals but the org as a whole, and especially the management, is responsible for mistakes.
Microsoft are trying to put a human face on what is a very cynical attempt to thwart web standards by slowing the growth of other web browsers. Their management have the resources to fix things but choose not to.
Too forgiving? The search components of the toolbar are superb. Better than anything else on the market, in my opinion. The tabbed browsing component doesn’t work right, but it’s a browser add-on from the MSN division. It is not from the IE or Windows team, which is working separately on the IE7 update, which will have tabs.