Trump and Cruz had a closed door meeting a couple weeks back. So far, neither camp has leaked any details of what they discussed.
In my opinion, those two are smart enough to have already figured out which way this race is going, and have concluded that they need to team up on a ticket together.
Trump is pulling support from across the political spectrum, while Cruz is a favorite son of the conservative right. Together, they'd be unbeatable.
It is a really intriguing combination. These two could fill in each other’s weaknesses to make quite a team.