Sounds pretty promising indeed, except that it still suffers from the same problem as its predecessor: the housing, while rated to -60m, has a curved lens optimized for above water shoots, resulting in rather blurry underwater videos [see FAQ]. Meaning an adapted or custom made housing is actually needed for diving, ranging from 30€ for a DIY replacement lens to 499€ for an aluminum housing rated down to -100m. GoPro's supposed to release its own flat lens housing soon?
Not to mention that for proper compositional framing, an optional LCD BacPac would be needed too. Upping the price tag to about 540€ (GoPro HD HERO2 Outdoor Edition @ 350€ + LCD BacPac @ 100€ + BlurFix adapter @ 80€ + tripod mount @ 10€). Not cheap, but then again, just getting a dome port for e.g. a housed compact system camera with wide angle would cost almost as much if not more.
→ GoPro HD HERO2 action cam
→ aquapixs GoForFocus flat replacement lens
→ Eye of Mine flat wide lens housing
→ Snake River Prototyping BlurFix adapter (flat 55mm wide lens port)
→ Subspace Pictures underwater housing with dome port (127° FOV)
→ sub zero flat lens housing
→ UK Germany UK-PRO flat wide lens aluminum housing (-100m)
→ interesting reviews of the GoPro HD HERO and HERO2
