Not specifically, but there is a workaround that may accomplish what you want (even if it isn't very convenient).
There is nothing in the UI to do what you want. However, if you know the appropriate HTML you can modify a draft and send that (which means first making sure that drafts are not sent immediately). Actually there is something in the UI which facilitates such a procedure: if you use the Two-line view for Message lists you can find the full path to a file via right-click, Properties.
Later once you have copies of messages sent using the "template" you want, you may be able to open these emails and merely delete the text and e-mail details and have the rest of it looking the way you want - but I'm not certain about this. Deleting the message may delete the coding at the same time - but I suppose once you have an example to work with, it's worth a try to see if it simplifies things or doesn't work as I am hoping.
Sorry, but for some unknown reason, they removed the option from WLM 2011. I don't know why, but I do know it cannot be simply restored or resolved with some minor registry modification. Using the above workaround (and once you have a set of HTML codes for different "stationery" types, it may become simply a matter of cut and paste with the appropriate code - though to be honest I haven't tried this and I'm not sure if it can be done that easily or if the coding needs to be done on a case-by-case basis with some editing involved beyond a simple paste). Still, it's the only workaround I'm aware exists at this time.
I hope this helps.
Good luck!