Monitor Lizard intelligence?

So Argo, my Roughneck Monitor, was hungry the other day. Now normally he gets fed on a regular schedule, but I have recently moved and everything was disrupted. So I've been late in feeding him (guilty as charged, I know) and when I let him out the other night to his exercise, he came straight over to my chair where I was sitting, looked up at me, jumped (he hasn't done that since he was a baby) into my lap, and started climbing around me, up to my head, then down my leg. Once down, he looked at me as if to say "I'm hungry, feed me darnit!" walked towards the kitchen (where he is fed) then back to me, and repeated this behaviour until the food I had thawing for him (steak) was done. Basically 3-4 times until his food was ready.

I found it interesting because at any other time, he doesn't really notice me or interact with me at all. So something is going on "up there" in his head, which got me to thinking, just how intelligent are Monitor lizards? Anyone ever do any hard research on this?

My experience with Monitors (Mostly waters) are extremely intelligent.

Deedle wrote:

My experience with Monitors (Mostly waters) are extremely intelligent.  

But in what way? Owner recognition? problem solving?

General intelligence

They're very observant, they definately problem solve, I believe they recognize their owners also as they build trust relationships.

I won't say it about all monitors but waters I have personally seen leash trained hell the one I watched for a friend was an adult about 5' and walked on a leash better than most dogs.