We have with our February CU also a SharePoint Designer 2010 hotfix package available.
2496947 Description of the SharePoint Designer 2010 hotfix package (spd-x-none.msp): February 22, 2011 http://support.microsoft.com/default.aspx?scid=kb;EN-US;2496947
Download link: http://support.microsoft.com/hotfix/KBHotfix.aspx?kbnum=2496947&kbln=en-us
Please be sure that you take the right binary version because we have 32bit and 64bit available.