Down to the details. The trial will run for three weeks and I will post up a thread for comments/suggestions a week into it when everyone has had a chance to get used to the mod and settled a little (read: thats not what this topic is for).
For the length of the trial the following restrictions will be placed on signature images:
Note that these restrictions may well change after the trial concludes. This will largely depend on feedback on size (in the thread mentioned above) and how well the admins feel the trial has worked, but for the duration of the trial these restrictions will apply.File-size of each signature image: 50 KB's.
Animated signature image(s) allowed: No.
Maximum number of images in a signature: 1.
Maximum dimensions of each image (width x height): 500 x 150 pixels.
By default all guests to the forum and all newly created accounts will NOT have signature images enabled. Users will need to go into their profile and manually change the option before they will be able to see any.
This means that those of you who wish to view signature images or make use of them will need to enable the option in your profile FIRST.
Forum moderators will NOT be required to have signature images enabled should they not wish to do so. Upon the addition of an image to a signature by a user forum administrators who have elected to participate in the moderation of the images will be notified via E-mail and they will be required to check the image and approve/reject it before it is ever displayed on the forum. In short, moderation of the images is being raised to the administrative level, so no burden falls upon moderators.
The board will automatically re-check all signature images in use every few days to ensure that users have not altered their signature image (i.e. replaced the approved signature with a porn image on their server to try and get around the system). If an image has been changed since its last check then the image will automatically be removed by the board and will require re-authorisation by administrators before it is displayed again on the forums.
To be absolutely clear even though it was stated above, animated images will not be allowed, ever

Provision is made for images that automatically update themselves over time (such as Xbox Live or Last FM signatures). Administrators can specifically allow the use of these images when approving them, to ensure that they are not thrown out by the board's re-checking (mentioned above).
I think that is all the important points I wanted to mention...excuse me if I missed anything out. Further information can be found in the FAQ, again thanks to Fahd, so should you have any more questions check there and if it is not answered feel free to post it here and I'll do my best to answer. You'll also all now find the new options (regarding enabling/disabling their viewing, etc) in your profiles should you wish to make use of them.
It is also to be noted that as of the time of writing there are a couple of bugs left to be ironed out, but hopefully no-one should run into them or any other issues. If you DO encounter any issues whilst using the forums which you feel may be attributed to this recent modification please let either myself or Fahd know. Thanks.
Lets all hope the trial is successful

- Anny