I'm not totally a fan of personas, because they encourage stereotyping, but they help designers create use cases, so they're relevant in most aspects of e-learning. This page is a decent introduction to the development and use of personas, and even has a link to a PowerPoint personas template. The idea is that the persona is based not on the stereotype but on actual data. "Having the right facts at hand can provide a designer with invaluable guidelines about what their ideal users actually want and will find useful. They can then build the app around the user rather than their opinion of what the user wants or should want, which can be quite subjective."