Three months ago we announced that we would not continue the development on multicolumn and we are looking for persons interested in continuing development on multicolumn. We did not find a developer which was interested and thus decided to mark the extension multicolumn as obsolete.
For adding multiple columns to TYPO3 please use the extension gridelements. If you have problems migrating your data from multicolumn to gridelements, please leave a comment or send an email.
In case you are interested in continuing development on multicolumn, let us know!