Graham, to clarify for region-locking:
Hong Kong, Japan, and the USA, are all the same region when it comes to Blu-Rays. A great boon to anime fans.
Now, a PS3 will not retroactively allow DVD's from all those different contries to be played on it (DVD region locking is entirely separate), but it will take any game or Blu-Ray movie from them equally.
(a further note is that many Blu-Ray movies from the major studios are region-free anyways, and all PS3 games themselves are region-free)
In short---having "region-locked" issues are fairly rare for a PS3. 20th Century Fox is notable for region-locking their movies--but again, US/JP/HK are all the same for Blu-Ray.