Man, they’re just cranking these things out. Just two weeks after iPhone OS 3.0 Beta 3 (which was, in turn, two weeks after iPhone OS 3.0 Beta 2), we’ve got another Beta.

Beta 4 of iPhone OS 3.0 is now available for developers, as long as they’ve downloaded the brand spankin’ new iPhone 8.2 pre-release. It just went live, so we’re not quite sure what’s new here. If you spot anything, let us know – we’ll do the same.

Also, it’s starting to look like we can expect Betas every 2 weeks until release. Next one ought to be on Tuesday, May 12.

Update: Details are still incredibly sparse, but here’s what we’ve heard so far:

• MMS now working on more carriers without modified carrier bundles (Only one report – still working on confirming this.)
• General performance updates, far less crash prone than the past builds.
• The “Store” settings pane now functions, allowing you basic control over your iTunes account
• API Change: “SKErrorPaymentNowAllowed allowed and was replaced with SKErrorPaymentNotAllowed”

More as we hear it.