Column (aka. block selection) mode has made it into Eclipse 3.5 (Galilei), and the two bugs below are closed. Simply use the Alt+Shift+A shortcut to toggle block selection mode as noted in the Galileo New & Noteworthy.
I have finally found some time to update the patch for Eclipse 3.4. The update site noted below contains patched plug-ins for Windows and Linux/GTK. Note that the update site only works for Eclipse 3.4.0, but not for 3.4.2, which you get as soon as you update from the Ganymede update site. I will no longer maintain the patch nor the update site as the patch has been accepted for Eclipse 3.5 (Galileo).
Eclipse Bugs 8521 and 19771 have over one hundert combined votes, resulting in one of the ten most voted for features of Eclipse. However, implementing Column Mode (aka. rectangular selection) is not easy and involves numerous API additions, namely to the StyledText class in SWT, which is already complicated to maintain.
There have been various attempts to fix this by simply adding a plug-in on top of eclipse, most notably columns4eclipse. However, these solutions do not offer the full functionality one expects when coming from editors such as UltraEdit.
In January 2007, Avaloq has sponsored the creation of a patch that implements column mode natively in eclipse. Due to the invasive nature of the patch and the fact that the API freeze for Eclipse 3.3 was already approaching, the patch could not be looked at closely. This site's purpose is to make a patched version of the required plug-ins available, in order to make it easy for interested parties to play with the provided functionality.
July 2008 – Chances that the patch will ever make it into the Eclipse trunk are rather small. By popular request, I have adapted the patch to Eclipse 3.4 and created an update site containing feature patches for the affected features in the Eclipse SDK. This should work for most text editors.
June 2009 – The bugs are closed, column mode is now called Block Selection Mode and part of Eclipse Galileo.
To try out column mode, add a new update site pointing to http://tkilla.ch/column_mode and install any items found under the new site.
To enable column mode, press Alt+C in any text editor. Alternatively, enable the Editor Presentation toolbar from the Window > Customize Perspective menu; then use the column mode button in the toolbar.
To uninstall, select Revert Configuration... in the Software Updates and Add-ons dialog.