Format for Merge Var "Date" type changing slightly

[jesse]

For the majority of people, this won't matter at all, but I want to
announce it just in case.

If you are processing "date" type Merge Vars, you are currently
receiving this format:
"2009-07-21 00:00:00"

ie, Y-m-d and then "midnight". Since date merge vars don't actually
store time in any manner, we are making a change deep in our backend
code (not related to the API) to remove the time. Starting later
today, you will start receiving this instead:
"2009-07-21"