We have a new 1.7 update to the Android Missing Sync now available on Google Play (formerly known as Android Market), which contains improvements to Proximity Sync, and a fix for an issue that had been seen on select ICS (Android 4.0) devices.
The big improvement, for everyone using Bluetooth or Wi-Fi to sync, is that we have dramatically improved how proximity sync works. There are now far more circumstances in which we can tell that the phone or tablet has come within range of the Mac or PC than in previous versions.
For ICS devices, we also fixed an issue where phones that did not have any physical keys were not providing access to the menu containing (among other things) access to the application settings. On tablets and devices with physical keys, this had not been an issue.