SELECT

http://www.google.com/support/forum/p/Google+Docs/thread?tid=5f7cf86dde5933b9&hl=en

B1: =QUERY( A1:A ; "Select COUNT(A) Label A '' " )

it appears that QUERY also counts the blank cells (probably 'seeing' them as zero-length strings).

Formula 1: =Query(A1:A100, "SELECT A, COUNT(A) GROUP BY A LABEL A ''")