It looks likely that iOS 4.3 will not be arriving until March. The evidence, although a little sketchy, comes from The Daily! No it is not an article in the app, but a subtle change in the subscription information. When The Daily was originally launched, you were given two weeks of free access. It was free because iOS 4.2 does not have the subscription services required to enable regular billing.
Now when you check your subscription information within The Daily, it is now showing as valid through 28 Feb 2011. As it is not a leap year this year, we can glean from this, that the earliest you can subscribe on a paid basis to The Daily will be the 1st March. Is this because iOS 4.3 will not be available until then? It's starting to look that way; despite the rumor that it would hit today. Looks like we will have to wait just a little bit longer for iOS 4.3!