Since I first used the XBee modules from Digi International I got questions from developers how to get higher ranges. Well, the XBee 802.15.4 modules I’m currently using have a maximum range of nearly 100 m. The XBee-PRO modules that are using 63 mW (+18dBm) power output could reach up to 1 mile (~1.6 km). In Germany you have to limit the XBee-PRO modules to +10dBm because of some restrictions in the 2.4 GHz band, so you loose some meters.
Digi International now offers the XBee-PRO 868 modules  which are using the 868 MHz short range device (SRD) GH3 band for Europe. With a dipole antenna you can reach 40 km, using a high gain antenna you should get a signal up to 80 km. The XBee-PRO 868 modules are pin-compatible with the XBee 802.15.4 modules which makes it very easy to choose the modules you need.
XBee-PRO 868 modules are long range embedded RF modules for European applications. Purpose-built for exceptional RF performance, XBee-PRO 868 modules are ideal for applications with challenging RF environments, such as urban deployments, or where devices are several kilometers apart. The XBee-PRO 868 features:
By deploying this and any XBee device, OEMs are leveraging the value of the XBee product family and Digi's unsurpassed Drop-in Networking offering of gateways, adapters and network extenders. In addition, XBee users can take advantage of platform agility, the ability to rapidly change their XBee solution with minimal development. Product summary:
I have ordered two development kits  each including two modules and USB/serial boards. Digi has an offer until end of February 2008: $99 USD compared to a single module that costs already between $69 and $72 USD. The kits contains:
+ (1) XBee-PRO 868 w/ RPSMA Connector + (1) XBee-PRO 868 w/ Wire Whip antenna
+ (1) RS-232 Development Boards
+ (1) USB Development Board
+ (1) RS-232 serial Cable
+ (1) USB Cable
+ (1) 868 MHz RPSMA Antenna
+ (1) Power Adapter
+ (1) 9V Battery & Clip
+ Various Adapters