i just got clued in on a new project from one of the members of the cDc (cult of the dead cow), a notorious hacker group from way back in the l0pht days. the wave bubble is a self-tuning, wide-bandwidth portable RF jammer. an internal lithium-ion battery provides up to 2 hours of jamming (two bands, such as cell) or 4 hours (single band, such as cordless phone, GPS, WiFi, bluetooth, etc). the battery is rechargeable via a mini-USB connector or 4mm DC jack (a common size). alternately, 3 AAA batteries may also be used. self-tuning is provided via dual PLL, therefore, no spectrum analyzer is necessary to build this jammer and a single wave bubble can jam many different frequency bands - unlike any other design currently available! to reconfigure the RF bands, simply plug it into the USB port of your computer and type in the new frequencies when prompted. multiple frequency ranges can be programmed in, each time the device is power cycled it will advance to the next program in memory.

its capable of jamming a few different frequencies:

cellular bands:

• GSM/PCS broadband 1900 downlink – (us standard)
• GSM 850 downlink – (us rural areas)
  GSM 900 downlink – (original and most common in Europe)
• GSM 1800 downlink – (gaining popularity in Europe)

other Bands:

• cordless phones – (900-930 mhz frequency)
  blue tooth – (2400-2483 mhz frequency)
• 802.11b/g wifi - (2400-2483 mhz frequency)
  zigbee – 868 (Europe) 915 (usa) & 2400-2483 mhz
• GPS – 1575.42 (civilian) and 1227.6 (military)

WOW!
this thing can block just about anything you can come up with!
for more info, including circuit diagrams, schematics, building instructions, parts lists, and firmware available from the inventers website http://www.ladyada.net/make/wavebubble