To date there have been three Krondor books published in the Riftwar Legacy series, Krondor the Betrayal (based on the story used for the computer game Betrayal at Krondor), Krondor the Assassins, and Krondor Tear of the Gods. (based on the story used for the computer game Return to Krondor). There were plans for 5 books in the series, the last two being Krondor the Crawler, and Krondor the Dark Mage.
At present Krondor the Crawler, and Krondor the Dark Mage are on hold, they have not been written, there is no immediate plan to write them.
There are issues with the current owners of Sierra, the producers of the computer games, that have not been disclosed by Raymond E. Feist, but suffice to say, until they are resolved, the final books, or book as it may become, may never be written.
26 July 2007 : More information can be found in Rounding up the Krondor books