1)she's got a bun in the oven (= she's pregnant)
2)they've got a bun in the oven (= they'
re an item and she's pregnant)
3)i've got a
new application in the oven (=i'm working on some
new software)
4)i've got a new project in the oven (=i'm working on a new project at the office, that is, in my day job)