You generally have 4 options to receive email,
1) from a corporate BES, which is almost instant
2) forwarded a copy from your mail server to the
( you don't need Gmail, your current mail server can do just fine) which is also instant
3) use the
which is also instant
4) set up your email on the webclient from your provider. You can receive email from up to 10 accounts this way, but this "polls" as seattle18 stated, I think Cingular it is a 15 minute polling.