Some users are reporting a frustrating bug in Gmail after receiving the Froyo update: while the primary account is functioning as normal, any secondary accounts don’t refresh automatically. Thus, those affected by the bug have to manually refresh their second account.
If you’re in this unfortunate group, take a look at the bug entry on Google’s mobile support forum. You can contribute with the behavior you’ve experienced and get tips on potential fixes andworkarounds. One temporary solution is to use another mail client, like the default Android Email app, or a third-party one like K9 Mail.
Because the Gmail app is closed-source, no one besides Google can poke around inside it and try to identify the problem; on the bright side, providing an update fix as soon as possible must be a priority for the Gmail for Android coders.