pgAdmin to display multiple result sets With MS SQL Query Browser I can run multiple queries at the same time and each result set will display in it's own window.

Does PostgreSQL/pgAdmin have this functionality? Plugin perhaps?
If started from the same SQL window, then no - you will always get the latest result set (or nothing, if the last command returns no rows, like in the case of COMMIT).  Not sure if this is OK for you, but you can open as many query windows as you want and so have as many result sets.

(The above means that I'm not aware any such plugins.)