Gossip says that "Martha Jones" will not appear in the first 6 episodes of Doctor Who however... she will be making several appearences in Torchwood and then will be in the last half of the 4th season of Doctor Who!
and to add to the mystery there will be a new companion for the Doctor who will be in the entire 4th series but who will it be??
Sources say they have not yet been chosen
do we need another girlie friend or shall be have a bloke?
I would quite like to see a fella zooming around time with the lovely Doc
just to make a change 
QUOTE
While the final episode of Series Three, screened last Saturday , saw The Doctor's companion Martha leave to care for her devastated family, and to break the cycle of unrequited love she feels for The Doctor, the production team has now confirmed that the character is set to make a triumphant return in the fourth series.
Freema Agyeman is also set to join the cast of Torchwood, where she will continue to play the character in three new episodes before returning to Doctor Who in the middle of the fourth series.
As Doctor Who's Executive Producer and head writer, Russell T Davies notes: "Series three has gained outstanding reviews and Freema has been a huge part of that success, gaining rave notices for her portrayal of Martha. Now we are taking the character of Martha into brand new territory with a starring role in Torchwood".
"I can't wait to start filming on Torchwood and the new series of Doctor Who," said Freema. "It's a huge new challenge for me and I'm delighted Russell has decided to expand the character of Martha Jones.'"
The new announcement leaves a vacant space in the TARDIS. A new companion for The Doctor, who will join the new series for the entire 13 week run, will be announced shortly.
Freema Agyeman is also set to join the cast of Torchwood, where she will continue to play the character in three new episodes before returning to Doctor Who in the middle of the fourth series.
As Doctor Who's Executive Producer and head writer, Russell T Davies notes: "Series three has gained outstanding reviews and Freema has been a huge part of that success, gaining rave notices for her portrayal of Martha. Now we are taking the character of Martha into brand new territory with a starring role in Torchwood".
"I can't wait to start filming on Torchwood and the new series of Doctor Who," said Freema. "It's a huge new challenge for me and I'm delighted Russell has decided to expand the character of Martha Jones.'"
The new announcement leaves a vacant space in the TARDIS. A new companion for The Doctor, who will join the new series for the entire 13 week run, will be announced shortly.
source
dont blame her