TheLadders was present at the NYC@Boston startup event a few weeks ago, which supposedly had to turn away some companies interested in being there. I'm surprised the people running the event would let a company like this recruit.
I wouldn't think a giant job and resume board needed this many people to run.
Looks like it would be very noisy too, headphones a must.
This is how you typically run a 'sales & marketing' office in NYC, by being open. Just surprised to see devs that are in that mix.
OTOH, as was pointed out earlier, it looks like a chaotic, noisy environment. If you have that kind of environment, you may need to multiply your team size by 1.5, at least.
edit: from http://careers.theladders.com/ it looks like they are using Java, Spring and are fully enterprisey buzzword compliant (only missing an Oracle RDBMS). If that's the case, you can multiply your team size again by a factor of 3.
edit 2: talking with a colleague from another company (they do a lot of Ruby stuff) I could confirm that our two-week sprints (we do mostly Java in this cell) are too long for them. Your iteration time varies according to the tools you use.