For various reasons, I like using POP with my desktop mail client (mail.app). The Pre, by default, uses IMAP. I don't even know if this can be changed or not, but I would prefer it be IMAP anyway on my phone, so it works.
In my Gmail settings, under the POP/Forwarding tab I have the setting for " When messages are accessed with POP" set to "leave the message in the inbox"
Apparently, this allows you to access your mail via POP without being destructive to any IMAP clients you may have. Without this setting, your phone would never see emails because your mail client will swipe them away every few minutes (probably) before your phone ever gets a chance to see them.
I haven't found any flaws with it so far and it seems to be working fine.
Just thought I'd share.