The vast majority of users of Scholarpedia have graduate degrees, however as the world gets more educated, Scholarpedia's audience will comprise a larger and larger share of the population.
Currently, Scholarpedia's users are scientists, graduate students, and other scholars, but the logo should not convey a sense of exclusivity or ivory-tower-ness: Scholarpedia aims to _increase_ the accessibility of advanced research and scientific knowledge.
The logo should convey, therefore, a sense of knowledgeable seriousness-of-purpose in combination with a sense of openness, wonder, and discovery. N.B. This last point is perhaps the most important of the entire specification.
Importantly, Scholarpedia's audience also comprises people of future generations. It should "stand the test of time", and thus avoid being obviously a product of current trends. This logo will likely continue to be regularly viewed in 10, 20, and 50 or more years' time. The logo's timelessness need not try and make the site look older than it is (it was founded in 2006): designers should think of how it will look, rather, to future generations. No one should look back on it and say "that logo is so Web 2.0".
Also, in line with a previous point, Scholarpedia's audience is very much international, even if English speaking.