I'd like to have symbols on the frame of an image in the library module...
... telling me which is the raw file, and which is the TIFF file from PS, so I can find my TIFFs and RAWs fast.[a href=\"index.php?act=findpost&pid=195578\"][{POST_SNAPBACK}][/a]
Are you talking about images shown in the grid view? In both the extended and compact cells you can tell LR to display the File Extension. Does that not solve your problem?
It's available in both LR 1.x and 2.0beta.
And an item in the filter menu to filter out the TIFFs from the RAWs.
Again in LR 1.x, it's not in the filters but you can do this by selecting the File Type in the Metadata Browser (down the bottom of the left panel). Given that you've selected a folder, All Photographs, or a collection to see the files in the first place, if you Command-click (control-click on Windows) the relevant file types you should get what you're after.
In LR 2.0beta, File Type is available as a column in the custom filters at the top of the screen.
I'd also like to be able to write a short comment on the frame of the image in the LR library module. 20 characters would be enough. Or maybe a button, that, when you click it, shows a note window, so you can jot down comments what to do.
Have you thought about using the Instructions field in the metadata? It doesn't show up on the frame of the image, but it does stay attached to each image and is accessible from other software (e.g. Photoshop) working on the file.