As of Jan 26th 2011, there is no fix yet.
It used to show new tab in 2007 but not in 2010
Site Aggregator web part: The site aggregator web part is actually a pretty simple web part – put it on a page and it can display all objects (images, documents, forms, excel spreadsheets) that have been added to any SharePoint site belonging to the same site collection as the one that the web part is deployed upon.
To configure it, you just enter the URL of the site that you want to display all the documents from, then give the link a name – this name then shows up as the name of the tab you click on to display the content from that site, so make it intuitive, eh!
So… under "Sites", click on the "New Sites Tab" – Enter in the URL and the tab name, then click Create.
New tab created, check!