I can't testify how many are fan-run today. But the annual summer Shore Leave at Hunt Valley, Maryland still is. Whether that would prevent Shatner from appearing, I can't say. Maryland's such a small state for big-headed stars. At any rate, Kate Mulgrew spoke there last August and she was magnificently witty. She said in her Q&A that the first memory that was going to stick with her from that weekend was the young teenage speaker who decided she was going to become a astro-scientist in part because of being inspired by Janeway.
You beat me to the punch. Shore Leave is a fan-run convention that routinely attracts stars. I chatted with LeVar Burton there just a few months ago . . . .