This is a feature request obviously.
987 posts should read 987 posts.
12,000 posts should be: 12k posts.
12.345 posts should read 12.3k posts.
1,002,567 posts should read 1mil posts.
1,242,567 posts should read 1.1mil posts.
Gives a cleaner look, and you could do more with typography this way as well; as large post counts wouldn't necessarily increase the space required. Excellent for mobile or responsive design...
It's not always desirable if you want the full data. Plus in some languages such as mine, it's a sign of laziness. :P
I rather prefer the full numbers too, its easy to misjudge 12.3k as merely 12.3. Reading it as 12.300 however, is instantly recognisable.