In preparation for my upcoming Visualforce course on Lynda, I discovered something that I think may have a big impact on some people out there that are using iFrames to embed a Visualforce page in the Sidebar. I have seen this technique used by several people over the years to display data in the sidebar and up until just recently the only way to accomplish this was to create a Home Page Component that referenced a Visualforce page using an iFrame. It was kind of a kludgy thing (sort of a hack really, so I am not surprised to see it go). I even wrote about this in a post back in November.
BUT, the release notes clearly state the following: