Not in any practical way with Aperture alone. Aperture provides a robust digital camera file workflow that stores, retrieves, and allows you develop each "photo" to be the most useful it can be for your uses. It is not a graphics application, and does not produce graphics files. For that you are advised to use any of the graphics programs out there. Popular ones are Photoshop and Pixelmator, among many others. Some are free.
Graphics programs are built from the ground up as compositors -- programs that allow you to combine different graphic elements (pictures, text, vector-graphics, etc.) to produce a new file.
You might be able to do what you want with the excellent BorderFX plug-in, which provides rudimentary but fantastically elastic compositing of Aperture Images with text and borders.