Visidon's Applock, today's highlighted app, touts itself as a cool way to protect your phone with face recognition. It's cool in theory, but disappointingly it's not very good at the protecting part.
You can select which apps on your phone you want to protect, and you have to scan your face every time you want to access those apps. It's great if you have something to hide, but it only works on phones with Android 2.3 and a front-facing camera.
I installed the app on a HTC Sensation this morning and gave it a spin. It wasn't long before we discovered that you could get past the security scan by simply holding up a photo of your face to the camera. I took a photo of myself on my Motorola Atrix, held it up to the front-facing camera on the Sensation, and just like that it granted me access to Facebook. It even let me in with the two-year-old photo on my driver's licence. It took a fraction of a second longer for the app to let me in at the highest highest security level (there are three to choose from - low, medium and maximum), but there's no doubt that your suspicious partner can find those incriminating sexts by just holding up a photo of your face.
My suggestion is that if you don't want your friends reading your emails and updating your Facebook status for you, go with apps that require you to enter a pin, and avoid anything that claims to protect your privacy by scanning (a photo of) your face.