I'm sure none of us would be silly enough to install an unsolicited application, but here's a heads up all the same: http://www.theregister.co.uk/2010/08/10/android_sms_trojan/ http://www.bbc.co.uk/news/technology-10928070
*waits for the apple fanbois to proclaim 'this doesnt happen on the app store!', even though it does*
I'm a fanboi, and I haven't mentioned it... I just think it's more important that people know about it so they can avoid it. Regardless of what smartphone OS they use.
I'm an iPhone 4 owner, and I know it can happen on iPhones too, App Store or not. There's this interesting exploit in the Safari browser, remember? Androids and iPhones Flowers of technology; Vulnerable all.