There is always XDA Developers for adding the update yourselves.
Note: The update from XDA-Developers is NOT for the faint of heart or non 'power users'. This process CAN brick your device. So proceed with utmost caution if you do choose to do the update. Also note if something goes wrong during the update process and you brick the device it is unlikely that any warranty for the device will be honored.
Don't count on Sprint to ever issue updates. If it's not Android they don't give a spit about supporting the device. Sprint has burned me with Moto Q, Palm Pre and now I'm sure they will do the same with the HTC Arrive. If it wasn't for Sprint being a cheap carrier I would switch. As for iPhone, Apple controls that and Sprint has no say so that's a good thing. Microsoft should have kept the same policy as Apple with forced updates.
I find it absolutely appalling (but, sadly, not surprising), that Sprint has said NOTHING about this update, including replying to complaints on their own forums. I can't wait until I start getting those phone calls in a couple months telling me to take advantage of my upgrade, so I can tell them exactly why I'm NOT doing it. They have screwed me on two consecutive smartphones now; they're not going to screw me for a third. That extra $20 a month to switch to AT&T is actually starting to look worthwhile, since I might actually get the value for it that I sure as hell am not getting with Sprint.
I know of at least 3 HTC Arrives that needs this update. It's not MS's fault that the keyboard issue hasn't been fixed but it's Sprint's. It shouldn't be that hard to release a bugfix update.
Bumping because Sprint needs to know we haven't forgotten, although I think after 14 years as a customer I'm through with them at my first opportunity anyhow. I've really had enough.
Mobile World Congress happens in Barcelona 2/27/2012 - 3/1/2012 - is it too much to hope for some information on this topic during that event?