There was an option to ignore stationery fonts in the older versions of Outlook via;
Tools-> Options...-> tab Mail Format-> button Fonts...
This dialog seems to be removed in Outlook 2007 and Outlook 2010.
Is there still any way to set this option?
There is no UI option for that available anymore indeed since Outlook 2007. You can still manage this setting via the registry though;
0 : Use the font specified in Stationery (if specified)
1 : Use my font when replying to and forwarding messages
2 : Always use my fonts
Note: For more information about how to implement these changes into the registry, see this registry guide.