Now, iPad 3G has reached customers hand, we can expect release of Spirit Jailbreak anytime soon. Until it is released why don’t you save your SHSH blobs in order to be safe in case ‘accidental upgrade’ for iPhone OS.
Redmond Pie has pretty good article about importance of SHSH and how to save it to be safe.

Below are 7 steps you need to follow to backup your SHSH:
Step 1. Open iTunes and plug your iPad. Back it up. When done, close iTunes and unplug your iPad.

Step 2 Download AutoSHSH.

Step 3: Put your iPad in recovery mode. To do so, turn it off, hold the home button while plugging iPad to the USB cable. Keep holding the home button until you see a “connect to iTunes” logo. If iTunes launches, close it.

Step 4: Launch AutoSHSH. Make sure your iPad is in recovery mode and connected to your computer.

Step 5: Click grab my SHSH blobs automatically. AutoSHSH will start to work.

Step 6: AutoSHSH will finally ask you where you want to save the file on your computer. Select a safe location.

Step 7: Reboot your device.

You have backed up your SHSH and safe now.