FYI, we've released an app which allows you to share pictures with other devices on the local Wi-Fi network (webOS or not). If you're sharing from a Pre3 or TouchPad to another Pre3 or Touchpad, you can initiate sharing using Touch-to-Share. Otherwise, you can initiate sharing using e-mail, IM, SMS or typing in the URL.
It requires webOS 2.2 or later.
Details and a video at Zap Photoshare