Custom Widget

So my theme came with some widgets that I can add to my side bars, and they work great. Recently I broke my blog off into three categories with sub categories so it has the feel of three different blog pages within one site.

My question is, is it possible to make a custom widget to do the following:

Right now there is a recent post widget, lets say my categories are Blog A, Blog B and Blog C. The recent post widget will list the 10 most recent no matter of the category so they are mixed together.

I’d like to make a widget to list the 10 most recent post from Blog A in one, the 10 most recent post in Blog B in one, and the 10 most recent post in Blog C as one. That way since they are all unrelated content I can seperate them.

Thanks for the help