Doing research with undergraduate is currently very valued: at small schools, as JSE points out, because it helps improve the educational experience f of your students. At larger schools, bringing in outside undergraduate students in the summer is a great way to advertise [recruit for] a graduate program. Including a solid undergraduate project always improves a grant application.
At the same time, undergraduate research cannot take the place of your actual research. I think that most people who are serious about UG research would agree that UG research in math should be primarily about the student's experience and growth, which means that more often than not the actual science will have to take a back seat to making the student a better mathematician.
It sounds like you're afraid you your CV has too much of that. You can rightfully boast about this, but (in an interview) I would make it clear that you don't intend it to be your whole research program.
Addendum: This is only marginally connected to the original question, but I thought I would mention a few useful resources for those who want to look into the what and how of undergraduate research.
- Pretty much every year including 2011, Aparna Higgins and Joe Gallian offer a minicourse, Getting students involved in undergraduate research at the joint meetings. A lot of what they do is to explain what to expect and how to get started. A lot of people seem to have unrealistic expectations (I imagine our OP does not since he has a track record).
- The UG poster session at the joint meetings is a good place to get an idea on what people are doing. Plus, they always need more judges! ;-)
- Remember though that the joint meetings poster session represents the cream of the crop, so check out your regional meetings, they usually have a poster session too.
- Check out the NSF REU site
- Here is an example of a non-REU program I'm familiar with. I'm sure there are more.URSI (Vassar)
This is in no way meant to be exhaustive of course!