I have been using a Seideo 2400mAH extended battery on my treo 680 for a while now, but recently tried a program to see the reported capacity. The treo reports it as a 1200mAH battery. When I insert a Treo 650 1800mAH Palm original battery in the 680, it reads the 1800mAH capacity.

For anyone who purchases extended batteries this is a concern. The Treo seems to only report the correct capacity of palms' own batteries. I used Hobbyist software's Power Hero to check it out and Handspring Battery 3.2 to see the reports of this.