iOS 4.0 is jumping all the way up a full tenth of a point to 4.1, and it's now available for those of you signed up for Apple's iPhone Developers Program. It looks like there are major changes to Game Center (which has yet to launch) in this build, but otherwise, we're not sure what's up just yet -- and no, as far as we can tell, there's no iPad support here. Stay tuned!
Update: So we're definitely noticing some differences. The signal bars are, in fact, larger in the new OS, and we're seeing fewer bars on our 4.1 device when compared to a standard 4.0 iPhone 4 (see the image after the break)... which is pretty much exactly what Apple said would happen. We're testing now and will report back what we find!
[Thanks to everyone who sent this in]