You can take this rumor however you would like, but a source that has spoken extensively with a member of the Xbox Live policy enforcement team has told us that one of Microsoft's big guns at E3 will be the announcement and possible display of future Halo titles. It has recently been made public by Bungie that they will be no longer working on Halo titles and have become a multiplatform developer. It has also been known for some time that Microsoft in house developer 343 Industries would be taking over the reigns on the series.
It's also no secret that 343 Industries has been hiring like crazy, and are with utmost certainty, working on something up in Redmond. A quick glance at the