I have noticed that there are a lot of people joining OSM just now. Larger numbers are always a good thing, but I do wonder at this time whether the anarchistic model will suffice in the future.
Not only could there be vandalism like Wikipedia's, but the "tag how you wish" approach could prove to be confusing and wasteful.
I'd say that the next 6 months will be absolutely critical for OSM. The work ongoing in changesets and suchlike for the 0.6 API is a step in the right direction.
I welcome opinions on the future direction of OSM.