I have just updated OTempo with a minor modification. It has now support for Android 1.5. This used to require the READ_PHONE_STATE permission on newer versions, because it was available by default in 1.5, but there is a simple trick to overcome this:
This way, the application will only require the permissions that you declared, and will be available also for 1.5 phones (I hope).
This has a drawback: the application will always have a warning about the minSdkVersion being lower than the project target API level in eclipse, but I will have to learn to live with this.