Broadband Femto Cell connects to GSM network over Internet connections

This isn't new technology but it sure helps to save overseas roaming costs.

A broadband device that behaves like a mini gsm cell station.

Wonder if the telcos around the world are blocking this service if connected from overseas...

An extract from Wikipedia definition of Femtocell :

In telecommunications, a femtocell—originally known as an Access Point Base Station—is a small cellular base station, typically designed for use in a home or small business. It connects to the service provider’s network via broadband (such as DSL or cable); current designs typically support 2 to 4 active mobile phones in a residential setting, and 8 to 16 active mobile phones in enterprise settings. 

A femtocell allows service providers to extend service coverage indoors, especially where access would otherwise be limited or unavailable. The femtocell incorporates the functionality of a typical base station but extends it to allow a simpler, self contained deployment; an example is a UMTS femtocell containing a Node B, RNC and in some cases GPRS Support Node (SGSN) with Ethernet for backhaul. Although much attention is focused on WCDMA, the concept is applicable to all standards, including GSM, CDMA2000, TD-SCDMA, WiMAX and LTE solutions.

Read more about some examples here
Mobile Barbarian: Verizon Femtocell