report_openoffice module has overgrown itself over this year, and got independence from ODT/ODS formats, it now can work with almost any document format as template - html/txt/EPL2 etc. So you can get all and even better results than with MAKO, Jasper, ReportLab reporting engines. BTW, for next OpenERP (v.6). Check all info regarding report_openoffice.
Seel also: How to edit Openerp POS receipt template, How to edit Openerp Sales Order report/template