Just wondering if our jpgs get compressed even more in the background when we upload to MM?

I uploaded some nicely colored shots tonight, then saw they got washed out when they were on MM. I had to go back to Photoshop and up the saturation to compensate.

Any tips?

Don't pump up the saturation.  Instead, right before you save it as a jpg, click Image ->Mode -> Convert to Profile... and convert it to sRGB.

Most web browsers are not color managed, so they screw up the way a lot of photos look.  Converting to sRGB before uploading does a decent job of saving your intended colors.

Thank you very much - I appreciate it.

Good info!  I found myself doing exactly the same thing!  Thanks.