The total number of voters on the first round of theme voting is usually fairly predicative of the number of entries. See:
http://www.ludumdare.com/compo/ld-21-voting-round-1-of-5/ Votes: ~650, Entries: 600.
http://www.ludumdare.com/compo/ld-20-voting-round-1-of-6/ Votes: ~400, Entries: 350.
So, after some fuzzy math, my guess is we’ll get 1000 entries this time.
Thoughts? I’m nervous!