You can double your work by adding tags (keywords) to your TIFFs in Picasa too. It’s a fun thing to do because Picasa will then allow you to search them. But, unless you are 100% done with your ‘real’ photo work and have time to add this as icing to your cake, I would discourage you from wasting your time on it.
Here’s what happens. Look at the Properties on a TIFF in Picasa that you know has embedded keywords in it. There’s nothing there. Now, add a tag in Picasa and look at the photo properties again (right-click on the thumbnail and select Properties) and you will see that it says ‘IPTC Keyword(s)’. This gives me some hope that Picasa is moving in the direction of becoming IPTC-compliant sometime in the future but I could be dreaming.
Unless they’re JPGs there’s no such thing as IPTC keywords in Picasa and they really shouldn’t be calling their tags by that name and confusing people. Or they should say upfront, Do not attempt to use this software for anything except JPGs.
The big problem that will show up if you add tags to TIFFs is that if you rename your photos outside of Picasa, you’ll find that your Picasa tags suddenly don’t fit the pictures. Picasa doesn’t know what IPTC on TIFFs actually is, so it’s blind to the work you do elsewhere. It’s smart enough to know how to sync the new file-names, but it doesn’t recognize the real keywords so it will leave its tags attached to the wrong pictures. And you will get to start all over again…
Has everyone got their trial of Photo Mechanic by now? All I need is a lifetime license to PM and one of those GPS gizmos that logs data to sync with my digital camera and I’ll never ask for another thing.