Ciscoworks in a multi-vendor network (juniper and cisco)

Ciscoworks monitors everything via SNMP, so as long as you have the correct MIBs loaded on Ciscoworks you can monitor any device. Many of the MIBs are generic anyway so you will be able to monitor all the basics stuff right out of the box.. The only issue you will have is that automatic discovery many not work properly because CiscoWorks uses CDP to do this. You can manually do the discovery but this can be tedious, and they also have a "seedfile" that you can populate to the discovery process. This same problem exists in pure Cisco shops that have MPLS networks because CDP doesn't propagate over MPLS links.

From a usefulness point-of-view, I would not use CiscoWorks to monitor your network. The name that people who use it call it "CiscoDoesn'tWork" because it is very buggy, not very scalable and doesn't even manage Cisco devices very well. Since you are a multivendor network, you should be looking at third party products that are much more capable and probably a lot cheaper.