For all our gripes about Microsoft's problems when it comes to branding, this one's kind of a no-brainer. It was announced this morning at Mobile World Congress that if a Windows Phone (See? We can stick with it) is going to run Windows Mobile 6.5, it's going to have to have that familiar little Windows "flag" on it to serve as a start menu button. [via] And the flag button will take you to the honeycomb hideout start menu.

Above, you see said flag on the new HTC Touch Diamond 2 and Touch Pro 2. And assuming Microsoft holds manufacturers to the "no flag, no 6.5" edict, this should be a pretty clear indication of what phones will get upgrades to 6.5 — HTC's Peter Chou said the Diamond 2 and Touch Pro 2 will get free upgrades — and which ones won't. (Phil looks down at his trusty Moto Q9h and sheds a tear.)

Update: OK, OK. We didn't mean that quite as literally as it read. At this point we have no idea what will be updated from 6.1 to 6.5, save for the Touch Diamond 2 and Touch Pro 2. The Palm Treo 750 has a little flag start button on it, but it's a pretty safe bet we won't see it updated to 6.5. It's more of a future branding thing, folks, not a litmus test.