This is good news for fans of HBO shows, but the real story here is the deal that HBO has reportedly managed to wrangle out of Apple. Portfolio's sources say that Apple has agreed to flexible pricing for HBO, which might mean we'll have to pay more than $1.99 per episode for that content. This is the structure that NBC, and many other studios, would love but Apple has been resistant to it in the past.
Before you go crazy, please note that flexible pricing might mean something other than paying more for the shows: Apple might give HBO a bigger cut of the profits from the flat $1.99. Only time will tell, since HBO insiders say that HBO's inclusion in the iTunes Store will be announced and launched at the same time.
Note: HBO and TUAW both have the same corporate overlords, but that doesn't mean we have any inside information.