HN highlights your username in orange to indicate that you're a YC founder, and shows that you're a founder of Octolane on your profile. Disingenuous comments like this on a forum like HN are strongly discouraged.
Huh? The username looks like any other to me. The only other color I ever see is green for new accounts.
HN gives three features to YC: job ads (see above) and startup launches get placed on the front page, and YC founder names are displayed to other YC alumni in orange.