Google Wave search operators, like Gmail search operators can be used to perform advanced search queries.

Here is an example: you can search all public waves about Ubuntu, by using this search query: with:public about:ubuntu. Or, let's say you want to take a look at all the public waves, then you would use this: with:public (or link).

But let's have a look at all (or most...) Google Wave search operators:

Keywords

about:[keyword] — finds waves containing [keyword]
title:[keyword] — finds waves containing [keyword] in the title.
caption:[keyword] — finds waves which have an attachment where [keyword] occurs in the caption.


Status

is:read — finds all read waves.
is:unread — finds all unread waves.
is:mute — finds all muted waves.
is:unmute — finds all waves which have not been muted
is:note — finds all waves which have you as the only participant and contributor