Guild Wars Nightfall

Chapter Three is an upcoming stand-alone product ("Campaign") of the Guild Wars game series, a follow-up of Guild Wars Factions (Chapter Two).

No title has been announced so far.

Content
Nothing is known about a theme or new content so far.

Release Date
No release date has been officially announced yet.

However, ANet hinted at the release date with two statements:
 * According to Jeff Strain Chapter Three has been in development since Nov 2005 (source) and the development time for each campaign is roughly 1 year.
 * ANet have stated that they plan to release two campaigns per year, released on staggered six month cycles. Factions (campaign 2) is due for release April 28, 2006.

Based on this, it is easy math to calculate the tentative release date. But keep in mind that long-term target release dates in the gaming industry are often optimistic and tend to slip backwards.