IIRC the swiping function of MicroB is present from the day one you got it, and you can use the swiping function although since the stock N900 has no portrait mode, swiping all the way from one side of the screen to the other is too hasslesome...

You start by putting your finger at one side of the screen and swipe the entire screen to the other. Note that you have to cover the whole screen (as in literally from edge to edge) and not just a portion of it for it to work.

As to what it does, here goes some nifty functions:

• Using your finger and making twirls on the screen: Zoom.
  • Clockwise motion: zoom in.
  • Anti-clockwise: zoom out.
• Swiping the screen from left to right: Brings out a mouse pointer in which if toggled, you can use it to select text. Useful when you have a large body of text you would like to highlight and copy.
• Swiping from right to left: Opens up your browsing history.