Can you bold-ify the first line of the about page?
I think that first line is more important than any other line (for stackoverflow ppl).
Assuming that by "Stack Overflow people" you mean users who visit Programmers from Stack Overflow... I don't think it's unreasonable to expect that people will realize that a different site would have different scope and might behave differently.
Programmers Stack Exchange is still a part of the Stack Exchange network and so is Stack Overflow. Both sites work the same in the sense that there's an FAQ that describes what the site is about. Anyone interested in finding out what Programmers is about just needs to check the FAQ.
Even when looking at the About page, I think it's reasonable to expect visitors to read the first sentence without it being bolded.
Incidentally, it looks like the About link in the top bar on the site has been replaced with a link to this meta site, so the About page is even less emphasized than before.
TL;DR: I don't think we should make the first line in the About page or the FAQ bold.
The first line of the about page is:
This is a free, community driven Q&A for professional programmers interested in conceptual questions about software development.
And the first line of the faq is:
Programmers — Stack Exchange is a site for professional programmers who are interested in getting expert answers on conceptual questions about software development.
I can't really tell which one you are referring to, both are equally important: The about page is worded to be a little bit friendlier to people who don't really know what StackExchange is and the faq page assumes you already know that and goes on to distinguish this from other sites.
Since you commented that your question is
for stackoverflow ppl, I'm assuming you mean the faq, as I think they'll probably skip the about page when first visiting Programmers. But it doesn't really matter, as the answer to bold-ifying both lines is: Nope.
Text Should be Scannable
Scanning can save users time. During the study, 15 participants always approached unfamiliar Web text by trying to scan it before reading it. Only 3 participants started reading text word by word, from the top of the page to the bottom, without scanning. Elements that enhance scanning include headings, large type, bold text, highlighted text, bulleted lists, graphics, captions, topic sentences, and tables of contents.
One user from Study 1 who scanned an article but failed to find what he was looking for said, "If this happened to me at work, where I get 70 emails and 50 voicemails a day, then that would be the end of it. If it doesn't come right out at me, I'm going to give up on it." "Give me bulleted items," another user said. While looking at a news site, one person said, "This is easy to read because it uses bold to highlight certain points." An essay containing long blocks of text prompted this response: "The whole way it looked made it kind of boring. It's intimidating. People want to read things that are broken up. It gets the points across better."
At first the quote may seem to support your point, but it doesn't: Bold should be used sparingly as a mechanism to enhance scannability and readability, and it's completely useless for sentences or other elements that already stand out. And the first line of the faq page and the about page stand out just because they are the first lines.
No need to emphasize more. Users that won't bother reading the first line, won't bother reading it even if it looks like that:
And I don't think it's worth spending any time emphasizing text for people who don't bother reading the first line of a text.