Good new for Sprint folks (remember, they're the ones with the HTC Arrive): your device is set to get that Microsoft "May" security update aka build 7392 on May 24th, which is just a few days away.
That update, if you recall, is just to fix some fraudulent third party certificates on the phone. In other words, don't expect any new functionality. However, it also looks to bump the bootloader to version 1.29.651.02 (currently it's at 1.24.230506), so who knows if that will bring anything new (we're not betting on it).
Considering we're about 2 weeks into the May update, Sprint's timing on the Arrive isn't half bad, especially considering this is their first update.
Source: Spantechular; Thanks, Mike, Joy and Sam, for the heads up!