For a minute there I thought someone had got 300,000 posts on thier own, which would be pretty strange... but yeah this is way better than those constant "I got <insert number here> posts, love me!" type posts because this is a milestone for all of TPM, think of all the memories in those posts. Also coincedentally the US hit the 300,000 mark for population this year. This year certainly seems to be the year for "300,000" milestones.
As for exams, no haven't taken them yet.
Edit: On a totally random note, with the "TPM Wedding" thread and now this one for "300,000 posts" the titles of threads here are starting to look a bit like a certian green site we all know and... well, know.;P