At least, that's what it looks like from their presentation on Handling Real-Time Datastreams at the recent Where 2.0.
They note that JTS does not have support for GeoRSS or GeoJSON. Actually there is a GeoJSON implementation sitting in the labs - but it really needs some funding to get it finished off (hint, hint, Twitter - what, you think this groovy open-source spatial stuff just codes itself?)
And as usual people have not noticed that the real source for JTS information is on the new home page and the Sourceforge site - not this stale web page. Sigh... if only URLs had expiry dates.