Gingerbread's built-in SIP client is great; I couldn't see a noticeable difference in battery life running it all day. Before Gingerbread, I ran Skype, which co

Gingerbread's built-in SIP client is great; I couldn't see a noticeable difference in battery life running it all day. Before Gingerbread, I ran Skype, which couldn't get through a full day on a single charge. Before Skype I tried SIPDroid, which was a lot better than Skype, but not as nice as the built-in Gingerbread one. My Skype account had lots of contacts and lots of chats open, so that may have had an adverse effect on battery life given that the communication is all P2P and required keeping an insane number of sockets open.