Well, if you're trying to help the 7100, bringing up battery life is not a good way to do it. ;)
Their website claims "up to 192 hours standby time" and "4 hours talk time". I've been frequently recharging mine since I can't afford to "test" the battery and risk being without a phone, but others have been saying they're lucky to get an hour's worth of talk time, and a "day's worth" of messaging before they have to recharge - a far cry from what BB claims.
I think some of the Sidekick's email is push -
or something like that, while the rest is just 15 minute POP3 polls, similar to the way BB does it.