Haven't tried it but ran across this:
From the California Avocado Commission:
Storing or Freezing California Avocados
Ripe fruit can be stored in the refrigerator uncut for two to three days.
To store cut fruit, sprinkle it with lemon or lime juice or white vinegar and place it in an air-tight covered container in your refrigerator. Eat within a day or two.
If refrigerated guacamole turns brown during storage, simply discard the top, browned layer.
When you have an abundance of fresh fruit, consider freezing it. Although avocados are not satisfactorily frozen whole or sliced, pureed avocados freeze very well and can be used in salads, sandwiches and dips.
Wash, seed and peel the fruit as described above.
Puree the flesh, adding one tablespoon of lemon juice for each two pureed avocados. Pack the puree into a rigid container, leaving 1 inch of headspace.
Seal and label the containers.
Freeze and use within four to five months.