The hit Doctor Who TV series will take a nearly two year hiatus between its fourth and fifth seasons because lead actor David Tennant is taking time off to do stage work with the Royal Shakespeare Company. 

The schedule for future episodes, according to the BBC, is for the fourth season to air in the UK in the spring of 2008 along with a Christmas special, three specials in 2009, and the fifth series in 2010.

The third season is currently airing in the States on the Sci Fi Channel and BBC America (see 'The Doctor Returns').  The impact on air dates and DVD releases of future seasons in the U.S. will undoubtedly take some time to play out, but it's clear that the flow of episodes and DVDs will have a significant gap at some point before the end of the decade.