After further analysis, more information has emerged about the Morcut Mac OS X malware which was discovered this week.
Clearly OSX/Morcut-A was created with spying in mind, as its code includes hooks to control/monitor the following operations:
instant messengers (for instance, Skype [including call data], Adium and MSN Messenger)
calendar data & alerts
address book contents
===> In short, if this malware managed to infect your Mac computer it could learn an awful lot about you, and potentially steal information which could read your private messages and conversations, and open your email and other online accounts. <===