MongoDB 3.0 is almost here. It includes the WiredTiger storage engine which is very impressive. Alas, now we are told that the original storage engine has performance problems. I am shocked. Who knew? Not anyone reading their documentation. I don't understand why companies play this game. Be honest with your users as this goes a long way to building a solid and educated community. I hold MySQL to the same standard. Lets us not forget that awesome manual section on atomic operations.
Don't let the marketing team have editorial control over the documentation team.
Edit: an era has ended, the section on atomic operations has been removed from the MySQL manual.