I think you noticed that already, but a couple of weeks ago I made a large change to the way community content is ranked. This roughly coincided with 1.25 release.
The problem was that the old algorithm was putting too much stress on number of downloads and ratings.
The new system takes into account a lot more factors than just raw downloads. Most importantly, the older the content gets, the more it gets downranked. I think this is good, because once something gets to the top of the list, it starts amassing hundreds of thousands of downloads and ratings. It then becomes even more entrenched at the top, other content never has any chance of dislodging it.
Now, with time working against it, anything near the top should not stay there for months on end as it was before.
I am still occasionally tweaking various parameters in the algorithm, but it’s not a major change, just small corrections.
I wonder if Google guys feel the same when they tweak Google Search ranking algorithm :-)