Apple on Wednesday seeded a third beta of iPhone OS 3.0 to developers with numerous unannounced/under-the-hood changes (which we will be detailing in coming days) as well as a handful of specific improvements developers have been asked to test.

Among the officially disclosed changes are:

*Overall performance improvements (removal of debug code, re-writing of several key system routines which have been identified as sluggish since firmware 2.0, some even going back to 1.x….also, a lot of attention has been paid to app launch times and fine-grained optimization of the graphics system which is most noticeable in visually intensive games or apps with very active visual interface behavior).

*MMS multimedia messaging now works properly on a range of foreign (mostly European and Middle Eastern) networks and is fully compatible with the alternative “carrier bundles” used by some service providers overseas. Read more