Session Tables

We are copying our existing Omeka database and creating new instances and our db was using a huge amount of space. Turns out the session table is enormous for our original instance.

I saw this post from a year ago:
http://omeka.org/forums/topic/omeka_sessions-table-in-omeka-153

Just wanted to confirm that clearing out the table will not cause any irreparable harm. Are there any potential consequences we should be aware of?

Yes, those still just store the user session info. Logged-in users will still be logged out, but since you are creating new instances of the sites, that makes sense to do anyway.