The 4.9 GHz public safety band is getting a workout: The band is allocated for first-responder government use, and many devices now support this 50 MHz-wide spectrum band. The Motorola WDE100, part of its Motomesh product line, offers both 2.4 GHz and 4.9 GHz in a single PC Card form factor. The card can work to extend an existing network to other peers--the word "mesh" is in Motomesh's name, after all--or establish peer-to-peer networks.
The Motomesh division seems to be the only company in the metro-scale/municipal space that's focusing on multimodal public safety equipment. Other mesh vendors have 4.9 GHz access points, but aren't in the adapter business. Motomesh appears determined to marry public standards with public safety and proprietary encoding, too. For instance, their four-radio access point uses their original proprietary standard on both 2.4 GHz and 4.9 GHz (one radio each) but then uses standard Wi-Fi on 2.4 GHz and adapted for 4.9 GHz. This allows one device to offer service to the public, municipal employees, and public safety workers. The new adapter neatly pairs with that idea.
This relatively new swath of spectrum is only legal for use by governments or government-authorized NGOs to "protect the safety of life, health, or property." Despite being allocated in 2003, it took some time to migrate existing government users off the band, and for manufacturers to develop a public safety market that asked for equipment in this range.
The 4.9 GHz band requires jurisdictional licenses, in which the jurisdiction over which a public safety entity has sway defines where they may operate, but it also requires that each overlapping authority in that region coordinate spectrum use.