I just recently updated my Droid to 2.1 and for the first time today, I started noticing some battery issues as well. Before that, it had always been fine on my phone and a couple of others I tested. Not all users may be impacted by the battery performance.
Normally, when the screen turns off and the phone goes idle, the phone goes into a lower power state where apps basically stop running until the screen turns back on. This is a problem for the Shaker app whenever a shaker is defined to respond when the screen turns off (for example, when the shaker is supposed to turn the screen back on). The app needs to stay active to wait for the user to shake the phone. Therefore, I am forced to prevent the phone from going into the low power state (using what is called a wake lock for anyone who might be interested). I will admit that this is normally considered bad practice as it can have a bad impact on battery drain, as we are seeing. I am looking for alternative ways of handling this, but it might take a bit longer to find an alternative to this with the current release of the Android Operating System.
I am working on some other ways of reducing the power as well. The next version will have the ability to disable Wifi when the screen turns off, which the phone should do anyway. Also, I may look into managing other applications I think may be using the battery while the shaker app is keeping the phone in its normal power state. For example, I think the live wallpapers are having an impact, so I might look to stop it from running when the screen turns off, and then turn it back on once the screen comes back on.
The last thing I have to say about the battery issues is that I will be asking for users to agree for the app to automatically send usage statistics back to me for analysis. Each user will be prompted in the next update to agree or decline. I will be gathering stats about the shakers that are set up, what is using the battery (and how much), information about running processes and apps, and general phone version information. Hopefully people will agree to send this information so I can continue to improve the battery situation.
If anyone out there has any tips, I am all ears!