Você pode dar uma olhada no Syrinx , um cliente do Twitter projetado para o Leopard (OS X 10.5+).
Aqui está o que diz:
Twitter Search: The ability to search all of Twitter is integrated
right into the client. Open a new
search window, search for a term and
receive a timeline of those search
results. Every few minutes Syrinx
will search for new results and add
them to the search result window.
Have as many search windows as you
want.
Growl Integration: Use Growl notifications to stay caught up on
your tweets without switching
applications. Click a Growl
notification to book that tweet, or
use it to switch to Syrinx.
O aplicativo é gratuito (donationware), embora contenha este aviso:
I am currently not accepting donations
for Syrinx development as it's a very
real possibility that Twitter will
soon force all non-official clients to
cease and desist. As such I can no
longer guarantee continued
development.
Não tendo um Mac, não posso testar este aplicativo