Nowadays you don't see quite often a company that will update all its Android phones. It seems HTC wants to take that roll, and at least update the phones that were launched this year. After updating all their high-end phones to Android 2.2, and recently the mid-end one HTC Legend, it's now Aria's turn to get a taste of Froyo. Unfortunately, as usual, Android phones don't seem such a big priority for AT&T, and it doesn't look like you'll get the update anytime soon. For now, only Southeast Asia customers will get the update. AT&T customers might get it sometime mid-January.
Android 2.2 can bring significant performance boost, as well an am improvement in how smooth the interface feels (better transitions). You'll also get wi-fi tethering, apps 2 sd, and live wallpapers.
Via – AndroidAndMe