Nokia Messaging is the new name for the Nokia Email Service which has been available in Beta stage for a while now.
The service essentially involves installing an email client application onto your Nokia phone which enables 'push-style' functionality on up to 10 POP or IMAP email accounts (such as GMail, Tiscali, Demon, etc).

"Under the hood", the email application uses the same engine that the now retired Intellisync solution used, so you also have advanced email synchronisation options including the ability to:

• Set an email synchronisation time period
• Set an email synchronisation date range
• Set a maximum email download size limit
• Set a maximum email attachment download size limit
• Filter attachment types
• Manage email folders (IMAP accounts only)
• Set an email signature
• Disable email synchronisation automatically when roaming

Supported phones currently include all of the Nokia E and N series as well as the Xpress Music phones.

The client application can be downloaded from the Nokia Messaging web site (https://netac4.vie.hosting.nokia.com/account/home.action) or is now preinstalled on most newer firmware revisions.

If the software is preinstalled on your device, when creating a new email account within Messaging --> Settings --> Email --> New Mailbox, you will have a option for the Nokia Email Service:

The resulting wizard will simply ask you for your email address and password, then determine the correct settings to use automatically:

The software will need a connection to the Internet to be able to download the correct settings to use. Once the set up is complete, your mailbox(es) can be accessed via the Nokia Email application, which is a separate application from the standard Nokia email client:

Additional mailboxes can be added by selecting the option to Add Mailbox and repeating the same procedure.
For those of you who used the Intellisync product for the Symbian platform, the Settings screens will look familiar:

Indeed, once installed, the Nokia Email Service application is listed in the running programs as 'Intellisync':

The Nokia Email service is free to try for a trial period - you will still be charged by your operator for the data involved in delivering emails to your phone. Once the trial period is finished and you wish to continue to use the service, you will need to pay for it. Watch this space for pricing information.