There may be an instance where you wish to create the Gantt chart directly within PowerPoint. The Microsoft Office Suite provides lots of integration between the various applications, and PowerPoint is no exception. By clicking on the Insert Ribbon in PowerPoint, you can choose Object. Then you choose to create a new object and in the list, choose Microsoft Project Object.
The newly inserted object will be a standard Gantt chart like you would expect to see within Project 2007. You can edit the Gantt chart just like you would in Project, and once you're through editing the chart, it becomes much like any other image object. You can drag it around the PowerPoint slide to position it where you want it. If you need to edit the data, you merely right click on the object and choose PowerPoint Object -> Edit. When you're done, you click anywhere outside of the object and it reverts to an image again.
From here you can dress up your slide by adding a Title banner, maybe a company logo, or even a descriptive text box if necessary. One thing PowerPoint provides in abundance is tools for effective presentation. Using the Shapes button on the Insert Ribbon gives you a multitude of options for dressing up your report. You can even add animation or sounds via the Insert Ribbon to enhance the document further.
Creating a Gantt chart in this manner is nice and easy, but it does require that you have both PowerPoint and Project installed. This can be a significant investment, so this is definitely a downside. But using this method, you can create your PowerPoint presentation as well as your Gantt chart without switching between applications. This also allows you to easily integrate your Gantt charts into a full-blown PowerPoint presentation, which is a very effective reporting tool for stakeholders.
If you'd like to see an example of a Gantt chart created within PowerPoint 2007, you can find one here.