There are some familiar names on our list of hot young companies, as well as some lesser-known mobile companies. These startups, most of which are two years old or younger, cover a diverse array of wireless markets, from wireless LANs to emerging markets like sensor networks and mobile storage.

Enterprise WiFi
Xirrus Inc.

Westlake Village, Calif.

Founded: 2003

Primary Product: A high-capacity, multi-radio WiFi box that can provide up to 1.2 Gbit/s of bandwidth to cover offices and other spaces

Funding: Largely self-funded, Xirrus took on an undisclosed amount of VC in January.

Xirrus Inc. is one of the few startups left in the enterprise WiFi space that is trying to do something outside the standard AP and controller model with a single wireless LAN box intended to provide wide-scale coverage for users.

Fixed/Mobile Convergence
DiVitas Networks Inc.

Mountain View, Calif.

Founded: April 2005

Primary Product: Fixed/mobile management systems

Funding: $23 million

DiVitas Networks Inc. is focusing its attention on delivering control of fixed/mobile convergence to the enterprise user rather than the carrier. The firm has already established an impressive array of partners with Symbol Technologies Inc. (NYSE: SBL) and -- supposedly -- Nokia Corp. (NYSE: NOK) working with the startup.

Mobile Email
Zimbra Inc.

San Mateo, Calif.

Founded: Late 2003

Primary Product: An open-source mobile messaging package that works with some of the latest smartphones -- such as the Motorola Q -- as well as established email devices like the RIM BlackBerry

Funding: $16 million

Zimbra Inc. is betting that open source will be the new wave in mobile email in 2007 and beyond. Mesh Networking
Meraki Networks Inc.

Mountain View, Calif.

Founded: April 2006

Primary Product: WiFi mesh gear

Funding: Undisclosed amount from Google and Silicon Valley angel investors, likely under $5 million

Initially spun off from the RoofNet group at MIT "with the hopes of bringing free or low-cost Internet access to people around the world," Meraki Networks Inc. made headlines late this year with its work with Google (Nasdaq: GOOG) to improve indoor WiFi mesh coverage at the search giant's municipal WiFi testbed in Mountain View.

Mobile Security
Network Chemistry Inc.

Menlo Park, Calif.

Founded: 2002

Primary Product: IDS and mobile security software for WiFi and Bluetooth networks

Funding: $25 million

Intrusion detection firm Network Chemistry Inc. is one of a select number of tech firms that can claim to be backed by the CIA. The investment arm of the U.S. agency contributed toward the startup's $6 million first round in funding.

Wireless Chips
Sequans Communications

Paris, France

Founded: September 2003

Primary Product: One of the first system-on-chip mobile WiMax chipsets

Funding: $35 million, plus an undisclosed investment from Motorola Inc. (NYSE: MOT)

Sequans Communications focuses on the smaller end of the mobile WiMax chip market developing silicon for mobile WiMax in handsets, base stations, and customer premise equipment.

RFID
Reva Systems Corp.

Chelmsford, Mass.

Founded: 2004

Primary Product: Tag acquisition network architecture and processor systems

Funding: $10 million

Reva Systems Corp. is trying to do for standalone RFID readers what the wireless LAN switch startups have started to achieve in the WiFi market -- prove that these devices can be centrally managed.

Mobile Storage
RingCube Technologies Inc.

Mountain View, Calif.

Founded: 2004

Primary Product: Software that can be downloaded to a USB drive and used to secure files so they can be safely viewed on any desktop

Funding: $4 million

RingCube Technologies Inc. promises to allow the user to access corporate office files securely at any time simply by inserting the USB drive into a workstation. Mobile Payments
Paymate

Mumbai, India

Founded: 2006

Primary Product: A system that enables mobile payments via phone text messages (SMS)

Funding: $5 million-plus

Paymate is hoping that the subcontinent will be the next boom market for mobile payments.

Sensor Networks
Tendril Networks Inc.

Boulder, Colo.

Founded: 2004

Primary Product: Technology that can find and manage sensors on automated wireless control networks

Funding: $6 million-plus

Wireless Sensor and Control Networks (WSCN) startup Tendril Networks is working on Zigbee short-range wireless systems to make it easier to wirelessly control automated tasks such as regulating the temperature of a warehouse and other applications that require constant monitoring.

Wireless in the Home
Ruckus Wireless Inc.

Sunnyvale, Calif.

Founded: June 2004 as Video54

Primary Product: Proprietary MIMO (multiple-input, multiple-output) antenna boxes to speed up video streaming over 802.11g for carrier partners

Funding: $30 million

2007 will be an interesting year for Ruckus Wireless Inc. as 802.11n technology becomes commercialized, which could help speed the spread of high-speed residential WiFi multimedia streaming networks.

— Dan Jones, Site Editor, Unstrung