On the home page, the link to the About page is not just prominent; it's very prominent. If the user comes straight into a question page without seeing the home page, there's still a somewhat-prominent banner promoting About, and there's a very prominent set of guidance for answerers that pops up if you click into the answer-entry box, as msh210 pointed out.
There may be a tweak or two that could make these measures a bit more attention-grabbing without being onerous, such as the forced click on OK that msh210 suggested, but as you note, there's a general tendency of users (of all electronic devices, programs, and fora) to skip past any sort of fine print as quickly as possible and get right into usage. I think that the present measures are sufficient to make the presence and friendliness of the About resource clear to any user who is at all inclined to use it, and it'd be difficult to come up with something automatic that'll force people who are not so inclined to take note of it that wouldn't also be very annoying to many people.
What I think we could do, though, is use our own welcome message practices to reinforce the value of the About and Help pages. Perhaps we could include a blurb about "If you haven't yet, please do check out About" in standard Welcome messages, though that may just come off as boilerplate clutter and make the rest of the welcome message seem more so. Instead, I think I'd recommend that any time we're addressing a new user whose posts seem at all problematic, we make sure to include an encouragement to review About and possibly [relevant sections of] Help, so they can get a better idea of what we're expecting. That would be a measure that's targeted both in applicability and content to where and how it's most needed, and it might help nip strings of problematic posts from new users closer to the bud.