Update 3 May 2011:
I've released new version for TesseractGUI (0.3) - the new version is using tesseract version 3 and it is linked against libtiff so it is able to open compressed TIFF files (packbits, lwz).
I've created a very simple user interface on top of tesseract.
It's available, along with sources under the MIT license, at: http://download.dv8.ro/files/TesseractGUI/
To use Tesseract GUI, open a TIF image.
After a couple of seconds, Tessertact GUI will switch to the text tab where it displays whatever it was able to recognize:
Nothing is saved, so if the recognition was successful you probably want to copy and paste it in some document.