I went one step further by removing the background OmaDrmConfigService from /system/app:
* EDIT * DO NOT REMOVE THESE FILES ! (read on to the next post, music and video playback crashes if this service is removed)
* DrmUA.apk/odex
* SisoDrmProvider.apk/odex
I also removed com.sec.android.app.samsungapps.una:
* UNAService.apk/odex
Based on what I read on the subject, I will probably get a few Force-Close when using the Samsung media player (which requires DRM for some media types), and it seems that Quadrant fails on H264+ video decoding...never mind, I'll see how things develop over time.
I should point out that this is not exact science, I am just experimenting based on feedback from other users, with similar Samsung Android devices. I may well make my Tab unstable in the future.
I should also explain that some self-restarting "start-at-boot" processes cannot be killed by "Autorun Killer", which is why I choose to move the APKs onto my SD card (backup...just in case). It is important to understand how "Autorun Killer" works by checking aLogCat output (apparently: 9 passes/attempts to kill the specified auto-run apps/services). For example, there's no point trying to kill unstoppable processes, as it wastes CPU cycles at boot time, and it may actually end-up generating instability in the initialization phase of the device. The "Autorun Killer" User Interface displays a list of running services, so from there you know that there is no point marking them as "disabled", because there is nothing the process killer can do about it => the solution is to uninstall the offending app.
GMail is a particularly annoying one, because I use the K9 email client in IMAP/Push mode, so I couldn't care less about GMail's Pull abilities, and I don't need it to run in the background. Maybe it handles contact synchronization, I don't know. At any rate, all of my device synchronization is configured to be run manually, I don't like automatic processes that launch arbitrarily in the background.

EDIT: well, I forgot to re-configure GMail notifications since I flashed JM6 (I wrongly assumed I had restored my old system settings using Titanium Backup). So hopefully this will cure it
As for SMS messages: I had to manually disable notifications in the "Messaging" system app, and enable them in "Handcent SMS" (which is the app I use for SMS/MMS purposes).