Dynamics GP and Dynamics RMS Integration? Yes.

There is inventory level integration between Dynamics GP and Dynamics RMS.

There is a free option directly from Microsoft for GP to RMS Headquarters:
http://mbs.microsoft.com/downloads/public/GP10Docs/RMSIntegration.pdf

Professional Advantage makes a GP to RMS integration that several GP Partners have recommended to me. (but I've not needed to use at this point yet)
http://www.profad.com/products/retail_gp.htm

For Dynamics GP to Dynamics RMS Store Operations it is a 3rd Party ISV Product:
http://www.nodustechnologies.com/retail_advantage.html

For those of you who have upgraded from Microsoft Small Business Financials this is just one of those many new things you can do that you couldn't before!