Nice if it last long since I'll get a ps3 someday.

doesnt matter, if your controller's battery starts going Sony will replace it. Got to love limited lifetime warranties.

I have three sixaxis since European launch (used alternatively most of the time) and they all last more than 25 hours per charge.

As with any rechargeable battery if you want them to last longer, you always have to drain them untill you are requested to charge again. If you shorten the charging cycle it will inevitably shorten your battery's lifespan, the same goes if you don't charge them when requested, the lithium-ion battery used in the sixaxis suffers irreversible damages if discharged below a certain voltage.

With an intensive but proper use the battery will only loose a few percent of its capacity after the first year, then the decline will be a little faster, but as the autonomy shortens the same goes for the charging time.

My old MP3 player used the same type of battery. I used the shit out of that thing every day for 4 1/2 years. It still had a 10+ hour battery life when I finally switched players.

Also I don't recommend taking the controller apart. I did it when I thought I broke mine and it's pretty much impossible to put back together by hand if you want it to fit snug like it comes.

My original sixaxis still works and can hold a charge and i've had that since launch. I'm not sure how long its lasts now, since i use the DS3, but 30+ hours is what i got out of it when i used it last, the same with the DS3. The controller also takes very little time to charge. Compared to the 360 or wii controller the PS3 lasts much longer.

The PS3 controllers aren't the easiest controllers to disassemble/reassemble, particularly the shoulder buttons/spacers, but I've stripped some of them down to the bare circuit board without too much difficulty. There are a few tricks to make it easier.

A full strip isn't necessary to swap out batteries, but it does mean having to disassemble the shoulder button assembly. Popping the two halves of the casing on the old six axis does require a fair amount of finger pressure between the two analog sticks if you don't want to snap the clip off (not necessary since the screws hold the casing halves together anyway).

But if Sony will replace them, no need to even bother unless you just like seeing how things are put together.

If you only charge them up when the power LEDs are flashing, they should hold a charge for years.

The guy at the store I bought it said if you used it every day, it would take five years to wear out.

That's pretty damned good.

EDIT: I believe he said 8 hours a day. Might have been exaggerating.

battery is replaceable but I broke my first controller changing it.  First controller didn't hold a charge very well at all.  New sixaxis holds a charge for days, especially now that they added the auto power saving feature.