The 26/11 Mumbai attacks, among other things, are a lesson to all of us on the importance of protecting the usage of technology and information.
If you recollect, the terrorists used GPS devices for steering the sea vehicle as they approached Mumbai. None of the terrorists had got formal training in seafaring but they were still able to come from Karachi to Mumbai. They used satellite phones during their journey and also in Mumbai in case local phone networks were jammed.
Their cell phones were Internet-enabled with switchable SIM cards that helped them to monitor police and media activities and also stay in touch with their bosses. The numbers that they carried were VoIP numbers so that the local networks are not able to tap into their conversation.
The scary part here is that most of the above technologies (with the possible exception of satellite phones, which again can again be ordered from the Internet for as low as $25 per week) are fairly easily available.
Besides technology, the terrorists also demonstrated innovative gathering and use of information required to conduct an operation of this scale. It is now confirmed that the terrorists had high-resolution satellite images of Mumbai which would have been used to get themselves familiar with the streets before arriving on Indian shores. They also appeared to have fairly detailed knowledge of the internal layout of the target locations.
This information could have been obtained from their accomplices who are rumoured to have stayed at the Taj and Oberoi Trident for a few days ahead of the carnage. It looks however unlikely that such a big operation could have been put at risk by having people roaming around the hotels collecting information. With the method and precision used, the possibility of the terrorists having detailed drawings of the Taj and Oberoi Trident cannot be ruled out. The few places where these drawings are available are within the hotel itself and with public authorities like the fire brigade department and the BMC.  
The other place where this information could be accessed is on Google Earth. It is easy with no security policy needed to view the images.
So what are the lessons learnt? Some of the measures that our public offices must take for prevention of technology usage for terrorism are regulating Google Earth and similar other services from displaying high resolution images of the Coastal Regulatory Zone (CRZ) as well as other sensitive areas. They should ensure that copies of layout drawings of public buildings are stored digitally and under high security. Having strict identity norms for users of public services like mobile and banking would also be a welcome step.