The SharePoint Team Blog has released some information on new rollup web parts to be included in SharePoint 2007. This is great news as the current version of SharePoint has practically no out-of-the-box options in terms of aggregating content from various team sites.
The new web parts allow you to roll up all the documents created, modified or checked-out to you as well as including all the tasks assigned to you. It is not quite clear from the post how configurable these web parts will be but it appears that they are limited to documents and tasks and based only on content relating to the current user.
I agree with Robert te Kaat's post that more flexible rollup web parts are desirable. For example, it would be nice if a parent site could display a list of all tasks aggregated from all the child sites or an aggregated list of high priorty issues. This is currently achievable with FrontPage and the data view web part, but a standard web part for this would allow numerous quick wins when SharePoint is used as a project management tool.