More points:
1) I searched for tags with the wildcard -*, which means "search for bugs without tags". Turns out there are 1032, many of them recent. I think these should be tagged because right now they're in no man's land. The number of 'pdf', 'ui', 'livepatheffects'... tagged bugs might grow considerably.
2) There are some tags like 'ui-text' that should be converted to 'ui text'. I think it's better that way because Launchpad's search already allows searching for multiple tags at once, while keeping them separate as 'text' and 'ui' at the same time. There are others like 'ui-toolbars-whatever' which are already covered by the broad tag 'ui'. My opinion is that this case should be simplified.
3) The tag 'bitmap' should be made official and used more extensively.
BTW, Launchpad was updated yesterday and the tag cloud is showing for everyone but, where are the official tags?
Regards.