I've heard, and recently read about a connection between juggling and
memorizing.  You juggle for a few minutes and suddenly you are able to
memorize things you couldn't easily before.

Have there been any studies done on if this is the case and, if so,
what is happening to cause an increase in memory skills?

(Google search: juggling + memorizing).

Oh man I hope that this is true!  (I've been an avid juggler for many
years...)

I haven't heard either way about this, but I'd hypothesize that any
short burst of physical activity might help - raising the pulse rate /
blood flow.

Also, it might make a difference if you were actively learning a new
juggling move as opposed to just 'going through the motions' with a
pattern you knew well.