No two situations are ever the same, with the exception of automated or semi-automated spammers. That pretty much always ends the same way.

For reference, here are the
Mobile Nations Community Rules & Guidelines. We're open to genuine discussion, responsive to positive changes in behavior, and the rules and guidelines are designed to promote healthy and interactive discussion rather than simply act as a list of punishments.
From the rules/guidelines:
[TIP]While our infractions system makes it CLEAR that some infractions can accrue to result in a ban, and other infractions can result in an instant ban... We realize that (from time to time) certain members may simply need a ?cooling off? period. To deal with this, we have a policy on banning for members that may simply ?go off the rails? once and awhile, in hopes of rehabilitating negative behaviour.
[...]
Offering members with a pattern of poor behaviour THREE CHANCES to rehabilitate themselves is more than generous. This schedule is to be executed at our moderators? discretion only and is a suggested course of action for those we feel can be rehabilitated into a productive member of our communities. In the case of flagrant spam, illegal activities, or other ?instaban? type violations, our moderators reserve the right to ban the offending member(s) permanently without notice.[/TIP]
As for users returning, I'll say this much: anonymity is part of the internet. It's always possible to walk down to your local library and register another account, change your IP address/browsers, etc. But the person remains the same. For the most part, they will exhibit the same behavior as they have done in the past, and involve themselves in the same forums and discussions. More often than not, users who are on extended or permanent 'vacation' realize that they didn't exactly fit well with the community, and either make a change in their behavior or simply leave it be. In my experience, users tend to be very responsive to the rules/guidelines and to the moderator team. We're not out to hand out punishments, we're here to foster a great community.
When a temporary ban expires or a permanent ban is repealed, the user's account remains largely unaltered; their posts haven't been thrown into digital oblivion.