If you mean pasting an image of part of all of a map in PowerPoint from MM2012, you can select the level of zoom and/or specific branch, click on the File tab, select the Export tab and choose Export as Image. The map will be exported as a bmp image which can be pasted into PowerPoint.
Alternatively if you are using Windows 7 or Vista you can use the snipping tool to clip a section of the map and paste that directly into a PowerPoint presentation.
If you mean converting a map to a PowerPoint presentation, right click on each topic you want to include and choose New Slide from Topic. Each slide created will display in the Slides pane on the left and can be exported from there to PowerPoint.
However, there are a number of limitations with this process, not least of which is the problem that the slides are a fixed size which means that only a limited number of sub-topics will appear on each slide, irrespective of how many there are on the map. As a stop-gap measure you can export the map as a Word outline and import tthe outline into PowerPoint.
