Looks like Apple's just released iPhone OS 3.0 beta 5, a little over one week after its last revision. That's about half the time they've put between the previous updates -- seems the boys in Cupertino are really starting to churn these things out. You know the drill by now, we don't know yet what the update entails, but we'll tell you when we find out. Oh, and just like last time, it appears iTunes 8.2 is required.
[Thanks to everyone who sent this in!]
Update: We can confirm that MMS "support" can no longer be turned on in Settings (in quotes because we could never get it working in previous betas anyhow), and we're hearing that trickery that allowed tethering to be enabled with the previous iTunes 8.2 build has been patched. Aww, you're no fun, Apple... thanks, Rene!