Hi all, another Droids user here. Many discussions on task managers and battery life showing up, I want to add my 2 cents here, since I've spent some time reading technical documents on the Android platform and trying to optimize my phone usage.
[REGULAR PROCESSES VS BACKGROUND SERVICES]
To make it very simple, we can divide processes on the Android platform into to categories. Regular processes and background services. Regular processes are the instances of all your visible apps while background services are something you cannot access directly with interface. Those background services are running background to provide some sort of "services" such as updating feeds, detecting the location, etc.
You may already know the Android OS kills background processes when it's running out of memory. When it kills, there is priority to decide which one to kill. As you might guess, background services have high priorities and except for very rare cases of resource depletion, the OS normally do not kill them.
[APPS WITHOUT BACKGROUND SERVICES]
The android platform give much more seamless interface than the iphone though, by providing the list of recently used apps and a mechanism for apps to save the "snapshot" if the OS has to kill it.
This type of apps use little resource, and actually it's hard to design an application doing lots of background tasks without services. For example, if I want to write an app for background downloading, I have to make a background service for it, otherwise the OS will randomly kill it and stop downloading when it needs more memory.
So, when you see some background apps other than service in task managers, you don't really care about them. And in terms of battery life and responsiveness, keeping them background actually helps since the OS does not need to relaunch them every time. This is why the stock OS give you the list of running services, instead of the list of all the background apps.
These processes are where the stability vs capability debate kicks in, and because apple does not allow 3rd party background process, the android platform are much more versatile than the iphone but possibly get some glitches if you use without caution. The apps we happily boast to our iphone user friends are those ones with background services such as Pandora, Meebo, Locale, Navigation, etc.
It is great that we have possibility of 3rd party background services, but be PICKY and CAUTIOUS when you use apps with background services. I usually get 2 background services running, Gtalk and Google voice, but sometimes things such as Pandra, MediaPlayBackService comming in.
If your battery life is really bad, try to single out the background service that uses up the resource. You can tweak the setting such as update interval, or try to find another app to replace with.
Also, try to use builtin Google apps over 3rd party apps as much as you can.
Builtin Google apps including the facebook app (but excluding the official Google voice app) use "push" technology to update, meaning it's Google server not the service in your phone which is continuously looking for an update.
For example, while the stock email app checks for new email like every 15 min, the Gmail app is just sitting there doing nothing until the Google server tells it that a new email has arrived.
If your email accounts other than Gmail provide forwarding service, I recommend you creating another Gmail account and forward emails to it. I didn't even set up the stock email app, and it does not even show up in the running services list.
Gtalk also consumes much less resources than other IM apps, but this is something you can't easily switch, so YMMV. Just try out couple of IM apps and find the one with the least resource consumption.
Hope this not too long to read!