Unless you've been hiding under a rock, you've heard about the so-called Windows Phone 7 "data bug" and Microsoft's response to it, with Yahoo firing back an explanation pinning Microsoft's implementation as the problem, claiming that only Windows Phone 7 devices suffer from this issue. Rafael Rivera, the one who first confirmed Yahoo! Mail as the cause, was not thrilled by Yahoo's answer.
An iPhone was used to pull data through the same monitoring script that Windows Phone 7 was run through, and the results? Almost the same, with Yahoo's servers returning an exceedingly lengthy reply to a request for message flags, consuming significantly more data than necessary, and causing the same problem as seen on Windows Phone 7.
You can read the technical bits on his blog here, but the important thing is this: The Windows Phone 7 data bug was a big deal, but did not necessarily need to be. Sure, Windows Phone 7's constant updating of data could lead one to large data charges, but with any smartphone, auto updating has caused numerous billing overcharges in the past. Whatever the reason why WP7 took the fall, call it a pride deal, but for us, we're considering this as an example of public hysteria. As for Yahoo, let's hope they fix their servers sometime soon.