70 CM HSMM?

What you are looking at is Ubiquiti's 2.4 GHz bullet. It's their simplest, and cheapest ($40) 802.11 device. It's basically a ethernet->N converter. Now imagine if it was capable of 420-450 MHz.  (Realistically something for this band would likely first start off in a mini-PCI configuration.)

Ubiquiti products are based on the Atheros chipset which allows you to reduce your channel width with to 5 MHz. This would fit in the lower 12 MHz of the band where ATV is allowed, and can still yield up to a 10 Mbps signaling rate. That kind of throughput can support live video feeds from IP cameras, Asterisk / IP telephony, and just about anything you can dream up.

When WiMAX platforms for operation around 3 GHz were in their planning stage, Ubiquiti acted quickly to provide a 3 GHz 802.11 solution for direct competition. That worked out well for us hams, as there is a 3 GHz ham allocation.    

WiMAX is much like ordinary Wifi except it uses licensed spectrum. Its for last mile connectivity, and the potential of mobile operations. Verizon wireless broadband is probably the most best example that most might be familiar with.
There are certified WiMAX platforms emerging for operation between 400-1000 MHz, covering the 70 and 33 cm bands, with selectable channel widths from 1.5 MHZ to 7 MHz. So a 400 MHz capable product from Ubiquiti or someone else doesn't seem that far fetched. 

If you have experimented on 2.4 GHz, you know how frustrating it can be trying to combat the high noise floor and plethora of Part 15 devices. When you utilize the channels unshared with Part 15, you still at best, are limited by the line of site propagation of those microwave bands. HSMM experimenters are usually few and far between so an organized approach to commercial tower sites is likely not the case. This is what would make a 420-450 MHz capable device ideal.

If the idea of 70 cm HSMM appeals to you, I encourage you to vocalize your interest. (Section managers and Ubiquiti sales seem like logical places to start :)

{Edit 4/11/10}
http://www.xagyl.com/store/product.php?productid=16450&cat=0&page=1

XAGYL FLR4G30 450MHz 1000mW miniPCI