This is what I've noticed over the last month of owning my Droid. I am a former iPhone owner and while I did enjoy my iPhone and loved what it could do, I love my droid more. The customization of the Droid makes it worth it for me. I use Home++ as my home screen which has a built in task manager. I use Google Voice and Google talk quite often. I rarely use Maps because I have not really traveled with my Droid yet.
There is a memory leak with one of the default apps or maybe Google Voice. Even before I started using Home++, I noticed my RAM will slowly drop to the low 30mb to high 20mb as available. When this happens, the phone drags and I have to either reboot the phone or kill some of the unused apps. This seems to happen mostly when using Google Talk. I am a Linux user at work and at home and I understand how Memory and resources are managed. Linux runs more efficiently than Windows ever did on the same machines. There is however an occasional need to kill apps.
My current 3rd party or none stock apps + widgets that have background processes:
Handcent SMS
Google Voice
Home++
Battery Widget
Brightness Level (Widget)
Beautiful Widgets
My battery life is pretty decent. I can go 12-16 hours on a charge when only moderately using the voice part of the phone and a bit of sms and gtalk use. I keep the brightness at the minimum level when inside; anything brighter is a waste of battery IMO.
Before I installed all of these extras, I did notice a drop in available memory when using gtalk. If I reboot the phone and let it start back up with everything running in the background that normally would be, it will start off with 100+ mb free, then slowly drop down to between 60-70mb. I can let the phone sit for hours, pull it out of sleep, unlock it and take a look at the available memory and it will still be at 60-70. The moment I start using gtalk, the available memory drops a great deal.
This was with ATK free and now without, the same problem persists. To make sure, I removed Home++ for a couple of days and the problem is still there. Something is leaking memory.
By the way, this is what my Home screen looks like. I love it.