To have a lot on one's plate means to have a lot of tasks and responsibilities.
We shouldn't give this task to Bob. He already has a lot on his plate. (Or: He already has a full plate.)
At Microsoft, this common English language idiom is treated as a normal part of the language. The metaphorical plate has become a synonym for assigned tasks and responsibilities and can be used as a basis for new idioms.
That feature moved off their plate onto ours.
Feature X got postponed to the next release, so there's room on our plate for Feature Y.
Update: Apparently there are some people who believe that Microspeak should restrict itself to jargon used at Microsoft and nowhere else. I employ a broader definition which includes the use of existing jargon which is used in an unusual way or used much more heavily than in the general population. Today's entry is one of the latter: I already pointed out that to have a lot on one's plate is a standard English idiom. What makes it Microspeak is how the word plate has taken on a life of its own at Microsoft, to the point where the original idiom is almost lost.
I apologize to those for whom this explanation was not necessary.