This week, Tivo has silently released its own branded wireless adapter for Series 2 Tivo units. The adapter features 802.11b and 802.11g access, as well as some circuitry that offers “Optimized wireless performance with your TiVo® Series2â„¢ DVR“. Essentially, from what I read and understand, the new adapter is able to take over some of the duties which are normally done on the Tivo unit itself, thus reducing the load on your Tivo and increasing throughput on the wireless side. A good discussion on the new adapter can be found at http://www.zatznotfunny.com/2005-12/tivos-wireless-adapter-arrives/
The adapter is currently available directly from Tivo and sells for $49.99.
UPDATE: The first review of this adapter is out and shows a performance increase of 60%!