best practice for connecting two building wireless

see

http://forums.cnet.com/7723-7589_102-340220/internet-sharing-through-wifi-between-two-houses-600-m-apart/

they are talking about cantenna's effectively

see
http://www.turnpoint.net/wireless/cantennahowto.html

Hi ,
You can use the Free Space Optics & Hybrid Optical-Radios
To get the optimum solution here you can find more info:
http://lightpointe.com/
I hope this suitable for you.
Thanks

Question is what speed do you need ... in general, the speed will be proportional to the money spent ... also, keep an eye on how confidential the information transmitted has to be - WLAN technology, which will be the most affordable for lower speeds (up to ~150mbit netto) is the easiest to sniff/capture, so even with current technologies like WPA2 you may want to think about putting an IPSEC gateway on each end. For 3+ GHz radio transmission, IR/Laser transmission, you have less danger of being sniffed, plus the higher priced equipment often has strong cryptography included, so no additional HW is required ...
Also, selection of technology depends on the weather and the required reliability - optical technology (IR/Laser) will suffer more under extreme weather like snow, haze/fog, or strong rain, whereas radio transmission will degrade less ...