As reported by MacWorld yesterday and several others, the Android marketplace was targeted with 50 fake apps that included malware:
Android Market spiked with malware-laced apps | Mobile | iOS Central | Macworld
Hackers took real applications, put spyware code in them, then rereleased the applications on the marketplace. Since Google does no checking of applications, it took a developer to notice and report the problem. In my opinion, Google has been naive with its Marketplace and has ignored the first immutable law of the Net. They do not have to be as strict as Apple with apps, but there has to be some level of review. Otherwise, their marketplace will be nothing but spam and malware.