Damn you people, you made me mess up my settings somehow.
For the record, push (or any push-like behaviour) was not working for me on either 3.0 Beta2 or pre-3.0 Beta2.
I got so hyped up, that I deleted my Gmail account, and proceeded to set it up as mentioned on the gmail instruction page linked here earlier in the thread.
Now I can't receive any emails on my gmail account. The inbox is empty, and the internet activity sign spins for ages and finally disappears. But still not a single email in the inbox.
All my accounts are IMAP, and I have Fetch set to Manually.
I noticed if I turn on Push, then none of the accounts can download emails, until I turn off Push.
Gmail however still cannot download emails.
Why did I read this cruel thread!?