There is a commercial app like the one posted above that does the same thing -- uses an SMS to trigger a Send/Receive from your inbox. It's called Push Effect by QoreFunctions. I'm not sure how much it costs.

QoreFunctions - Nifty little apps that make life a little easier

There is also another company offering a free push mail solution for people who don't have an exchange server (i.e. Yahoo Mail or Gmail). It's called Consilient. When you enter your mail info, download the software and install it, it creates an account called Push in Pocket Outlook and e-mails sent to whatever account you set it up with (I tried with Yahoo) will be received immediately. The only catch that I can see so far is that e-mails you send out will have a small text ad tagged at the end. I assume battery life will also take a hit since it's real push mail.

Free Mobile Push Email - Consilient Push

Anyway, those are two options that are somewhat similar to what was discussed earlier. There are also options for true push if you're using an exchange server or Emoze if you don't mind leaving your computer on.