Back in 2010, the registration of the TransformersDarkoftheMoon.com domain name by brand protection agency MarkMonitor was what revealed that film's title to the world.
Now, the same agency has now registered three more titles, leading to speculation one of these will be the title for Michael Bay's upcoming fourth film in the series. The three titles:
Transformers: Last Stand
Transformers: Future Cast
The third doesn't really sound like a film title though, so it's a good bet it's one of the first two.
That said, Bay himself has been quick to shoot down rumoured titles before. A report earlier this Summer of the title "Transformers: Rise of Galvatron" was shot down by Bay who said any new title he would announce on his website first.