A nice improvement on My Sites in SharePoint 2010 is that all of the My Site content and pages except "My Content" is now provided by the My Site Host site-collection, and not as in SharePoint 2007 where all except the public profile page UserDisp.aspx was provided by each user's personal site-collection.
This makes it much simpler to customize the content, links, web-parts, and look and feel of My Sites in 2010. Just customize the shared pages in the My Site Host such as "My Profile" and "My Newsfeed", save/deploy and the changes will immediately affect all My Sites. No more hassle of pushing the profile customizations to thousands of personal site-collections. Note that the "Tags and Notes", "Colleagues" and "Memberships" are stored in the /_layouts/ folder and are application pages, not web-part pages, and as such are not easily customized.
Any customization needed for "My Content" will still depend on e.g. feature stapling or master page delegate controls to push the changes to each personal site.
See Customizing My Sites in Microsoft SharePoint 2010 on the SharePoint Social Computing team blog for an overview of My Site customization options. See also the 1h42m web-cast Customizing My Sites and Social Features in SharePoint 2010.