Hi Chris,
You can use all our AJAX controls in SharePoint 2007/2010 sites and the following articles from the online documentation illustrate how this can be done:
http://www.telerik.com/help/aspnet-ajax/moss-deploying-radcontrols.html
http://www.telerik.com/help/aspnet-ajax/moss-incorporate-radcontrols-in-moss-sites.html
http://www.telerik.com/help/aspnet-ajax/moss-create-ajax-enabled-sharepoint-webpart-radcontrols.html
For RadTabStrip in particular, you may consider using the same approach presented in
this topic which explains how to replace the default Quick Launch Menu with our AJAX panelbar (reusing the same data source).
In addition to that, you can utilize the SharePoint 2010 web parts included in the
Telerik SharePoint Acceleration Kit (currently in CTP stage). I encourage you to try it out and share your feedback with regards to the components/features included in its present version.
Best regards,
Sebastian
the Telerik team