Season 10 starts July 19, 2010 after the movie "Degrassi Takes Manhattan" airs. The format for Season 10 is going to be more like a soap opera in that it will air new episodes each day (4 new episodes a week). Looks like it will be an interesting season.
As for the TeenNick promo, I think the commercial was to give us a little taste of what we can expect in Season 10:
Holly J--ringleader, may mean she is going to still rule at Degrassi
Riley--top jock at Degrassi and may have some new competition (from that guy that takes the hammer from him)
Adam--new character--The person in the house of mirrors is transgendered (the first on Degrassi). He is male, but may actually feel that he is a female. Hence the female in the mirror. Just found out that the character is played by a female actress, so it could actually be that she was born female, but prefers to be seen as a male.
Sav and Holly J (knife throwing)--*speculation* maybe Sav gets into some trouble and Holly J has to help him; could cause sparks (potential new couple) or maybe she helps him and expects him to repay the debt??
Bianca--"The Girl Who Makes Boyfriends Disappear"--looks like she will be making trouble for existing couples or just one couple on the show.
Anya--"The Two-Faced Girl"--maybe they will be exploring Anya's bad side, since we've really only seen her as the good girl.
Jenna--"The Girl Who Doesn't Know Her Own Secret"--not sure what this will be implying, but it looks like it will cause her and K.C. to break up.
Leia--looks like she will be back for season 10; maybe she'll get a storyline or she may just stay a supporting character
New guy (looks like a new bully) will be picking on the "nerds" of Degrassi.
Claire (with another new character, Eli, and potential love interest)--as the fortune teller reveals two cards "The Lovers" and the "Death" card. "Lovers" card could refer to Claire and new guys relationship and "Death" could refer to one of them dying (I hope not though). Or it could refer to another pairs relationship and death of another character on the show.
Alli--in the kissing booth--may get new love interest (Riley's rival--named Drew); and Dave missing his chance with Alli.
Fiona--covering up a black eye; she may be in an abusive relationship.
The spinning wheel--"Where It Stops...Nobody Knows"--has words such as: Crushes, Betrayal, Seduction, Surprises, Lies, Love, Danger, Secrets, Loss, Deception, & Lockdown (which it looks like it may land on...possible foreshadow to a lockdown at Degrassi?)