All of sudden it wont charge iPhone 3G

Argh!
I plugged in my iPhone the other day for an hour… but nothing happened. No charge. Weird. So I plugged it into my other wall charger, but still no charge.
The weird thing is I get the ding! and the charging icon in the upper right hand corner of the phone has a little lightning bolt in it. But still the BIG battery never moves.
Ive restarted, and reset several different ways. Even gone through the motions w/ the on-phone technical help people. But nada.
The really weird thing is I shut it off last night, plugged it in and prayed. And it was full this morning!
But now its not charging again. Ugh
Im not opposed to taking this thing apart, because its obviously a hardware problem (right?), but I dont know if my battery is bad. Could it be a connection to the battery? Is that something that could shake loose or something?
BTW, Im out of warranty by a few months. If that matters.
Any ideas?
tx,
e
3.2GHz 8-Core MacPro Mac OS X (10.6.1)