On Sept 17th, the MI5 Director-General, Jonathan Evans, gave a speech before the Worshipful Company of Security Professionals, regarding the use of cyberspace in espionage.
In his speech, he addressed the major threats the domestic intelligence services faced. This includes the use of the internet as a vector for espionage. The increased use of the internet for espionage reduced political risks for nations to engage in the activity. As a side note, the cyber-espionage can pave the way for tradition forms of espionage.
(Source: Stratfor and telegraph.co.uk, Jonathan Evans' terrorism speech)