The format of date tooltip for clock applet by default is read as "Воскресенье 12 Июль 2009 (Sunday 12 The July of 2009)" which is incorrect. Correct form is "Воскресенье 12 июля 2009 (Sunday 12 of June of 2009)", i.e. with month name in Genitive case and not capitalized. Even Windows shows date correctly...
That is not a bug in the panel. We simply use strftime to parse some date format, same as the date command, for example date +"%A %d %B %Y".