Listening to the audio provided under amp88's link, it sounds like Hamilton is simply trying to establish whether or not he should be letting Trulli through.
Trulli drops it in front of him, and Hamilton goes past. He then asks over the radio if he needs to let Trulli back through because he assumes that when Trulli lost his place, they were under safety car rules. The team then say hang on, we're asking Charlie (who no doubt is frantically thumbing his way through the rule book for the answer). Given the events that took place last season, I can understand Hamilton's concerns over getting this right.
Presumably the key question at this point was, do we have to give the place back to someone who 'drops' it under the safety car?
So the team play it safe and let Trulli through.
The race ends.
OK. Here's the confusing bit.
After the race it's discovered that Hamilton did not in fact have to give the place back. (I don't know why - maybe because Trulli dropped it or maybe because at that time they were not yet actually under the safety car rules. Whatever. Perhaps someone can tell me.).
It turns out that Trulli got his place back in error, and that the correct result should have been Hamilton 3rd and Trulli 4th, so McLaren ask for the place back.
Yes, McLaren made a bad call at the time, and shouldn't have let Trulli through, but if you listen to the recording you can clearly hear the confusion present at the time.
But is this actually 'cheating'?