This past Friday, Google was displaying a new filter in the main Google search tools for showing personal results only. This feature was live for anyone with a personal Google account who was signed in while doing searches.
Here is a screen shot of the feature:
When you selected the “Personal” drop-down option under the search tools, Google would then filter to show you your emails, photos, flights and other personal data related to your query in the Google search results. Here is a screen shot of Google showing me my personal emails for my Gmail account that I rarely use:
This reminds me of how Google had Search Plus Your World, where Google would surface personal Gmails and other items directly in your search results. This feature was launched in January 2012 and has come out from time to time since then.
Again, this would have worked on Friday if you were signed into a personal Google account. If you searched while signed out or with a Google Apps account, it would not have worked.
As of this morning, the personal search tool filter seems to have been removed.
We did email Google for a statement about this late Thursday night and have yet to hear back.
Postscript: Google has confirmed this as an experiment and sent us this message:
We are always experimenting with ways to make Google Search more useful for our users. At this time, we have no further plans to announce.