Yes, OOo 2.4 is being developed right now and the latest update up to now is M6 snapshots (it's being planned to be released next month). It contains quite a lot of changes compared to OOo 2.3.1. You can check the detail on this Release Notes (please note that this version is prone to changes when new release has been published). Some noticeable changes are:
- More print option in Calc : The Print dialog in Calc gets extended by a new possibility to define what part of the spreadsheet has to be printed. In the current version the print setting "print only selected sheets" is located in the Options dialog of the Print dialog and got defaulted for OOo 2.3. This raised several new issues around print output is empty when the corresponding table was not selected in the spreadsheet and the setting itself was overseen/unknown in the Options dialog.
- Support of background image on Impress : Lots of people are starting to use a huge amount of large-scale images in their presentations. But there wasn't any approach how to simply add a picture on a slide background. This feature should use a simple right-click way instead of a complex page format dialog.
- Separate zoom per sheet : This specification documents changes made to the Calc options dialog.
- Support for backward references in Find and Replace : The usage of backward references in regular expressions allows powerful find and replace algorithmns. E.g. It is possible to find and replace dates in differents formats like DD.MM.YY into MM/DD/YY.
Check the OOo 2.4 schedule release for more information about the publication date