I'm pretty sure season 3 of Newsradio has not been announced because I just looked the other day and could not find any info about it anywhere. With as long as it took them to get the first 2 seasons out i'd guess it'll be out in 2008
Seasons 1 and 2 have barely been out for 2 months Sony doesn't usually announce things that quickly. I'm sure you'll get more, and I hope we get more b/c I'm really digging this show right now, but I wouldn't expect to hear anything until towards the end of the year at the earliest.
NewsRadio came out at the the same time as Seinfeld season 4 last May. To be on track with a six month release schedule, both Seinfeld and NewsRadio would come out at the earliest in November. November releases will not be announced for another month so it is hard to say. I am expecting a Seinfeld season around November as popular as that DVD sale is. I'm not sure how many units NewsRadio sold but hope it is released on the same month as Seinfeld.
The reason I say this as if the six month cycle comes and goes with no NewsRadio, it may be on one of those once a year type scedules as are some other TV shows and then we would be looking at May 2006.
Another thing here is that it took a long time to do the extras for seasons 1-2, and they probably didn't do anything for season 3, because that depended on how well the first release sold. So if it sold well enough to justify more seasons -- and I suspect it did -- there'll still be another hold-up while they record more commentaries.
Seinfeld is currently on a six month release schedule with a ton of extras for each season. Hogan's Heroes and Bob Newhart are also on a six month release schedule and they both have extras for their second seasons. I hope it does not take a entire year to put extras in for NewsRadio but I guess we will all find out in September when companies let us know what is on the release schedule for November. I believe that if it does not get released in November, we may not see it until May 2006 as companies usually like to be very orderly in their releases and like to release things quarterly, semi-annually or annually.