Technical Evangelists areeclectic people . Many companies have them and many evangelists do their jobs completely differently. This is because “technology evangelist” has no setdefinition of what the job is. The bestexplanation of what they do is being the special operations division of a company. They solve whatever problem theircompany faces in relation to technology, the public andinternal culture. Evangelists have to be very good programmers to be successful. Evangelists must also be skilled at communication, as they are at the forefront of their company and any actions they undertake could be interpreted as a gesture by their company as a whole.
Some evangelists are essentially celebrities and direct the perception of their company thanks to gravitas of their persona. Examples of such would be Robert Scoble, Guy Kawaski or even Steve Jobs. Everywhere they go, people are all ears to see what next move Apple or Microsoft is going to effect.
Other evangelists are teachers and solution solvers. They meet with developers, designers, students, businessmen and all other assortments of people and they show they how they can take advantage of a certain platform. For example, a Twitter evangelist might work with a municipal government to come up with a more effective way to communicate with a neighborhood. Notices sent via Facebook and Twitter could save millions in communication expenses and help the environment by reducing paper waste from letters.
Another variety of evangelists are those who try gain critical mass for their platform or technology. Mozilla does a lot of this, they try to encourage an open web where infrastructure standards are not taken hostage by any corporation. Microsoft evangelists did similar work in the past to promote Windows as the_de facto_desktop operating system for the world.
The work evangelists do is not purely external. They also have to work towards changing the perception of the public vis-a-vis with decision makers in the company. For example, Robert Scoble petitioned Microsoft to buy Skype (not only him) and others encouraged Microsoft to adopt open-source practices.
With evangelists there are no sales quotas to hit. In fact, there are generally not many hard metrics, though this may be less the case with a startup, as theymight be expected to take on multiple roles such as sales or marketing. An example of a metric would be getting 50 researchers to try out a cloud platform. This would require more than just walking up to a professor and making him try your platform. The person wouldhave to first spend some time talking with academics to see what kind of problems they have and then try to see if hehasany solutions for that.
The career prospects of an evangelist are diverse. Thanks to the nature of the work, evangelists usually have way more connections than an average employee of company X. They have good relations with partners, competitors, customers, coworkers, superiors, the media, organizers of tech events and the public in general. This means that once an evangelist moves on from her job, she is easily considered by many other employers, especially if she was a competent and helpful evangelist.
But someone has to manage the evangelists soas evangelists are better than most non-programmers at code and better than most programmers on the business side, they make excellent candidates to take on management positions.