If all you do is root for SU access, then you'll be fine with future updates. I rooted my Iconia and received the OTA update about 10 minutes afterwards, it did not remove root.
If you root AND remove any of the pre-installed software, even the Link to Adobe Flash and Link to Facebook, then future OTA updates will fail as the system checks to see if these are installed prior to applying the update. You'll have to reinstall the bloatware, then apply the update, then re-remove the bloatware. It's a PITA, I know, but its something we have to suffer through until Acer unlocks the bootloader so we can install custom ROMs. Right now, the encrypted bootloader is the main hinderance to further progression on development.
I recommend that if you root to remove any bloatware that you back up the APKs and the ODEX files before removing them. This will save you a headache when we get the 3.1 update - its rumored to come in early June.