Are blogs the new gate-keepers?

Maybe in economics, yes:

Marginal Revolution, Tyler’s blog with Alex Tabarrok, is a new alternative to the traditional gatekeepers in economics — the journal editors or the program leaders at the NBER. Tyler and Alex earned this position simply by being good at what they do. Adding sites like this may do more to increase competition in the space of ideas than traditional strategies such as creating new journals. A mention from a site like MR is now an alternative way for new ideas to get attention, one that can parallel the traditional mechanisms.