@winkler: Yes, we too think that categories are one of the essential features.
Referer: Yes, we thought about showing the referers at the bottom of each daily post, instead at the bottom of start. Clearing the referer list from time to time at specific posts (or downgrading the count) could be done (although I don't know how to do this in a senseful way).
@omoikane: We run SnipSnap with aprox. 3500 Snips right now without problems (and with no crash). The cache policy is write through, but there might be problems with the default database (McKoi) because I can't predict the write-through policy of the database (You can use another one). Security might be a problem. We have not done a security audit yet, we will do one when we have reached beta because right now several things might change.