Activate Mass Effect 1 on Steam
According to Steam Support, no.
you can't activate it on steam, but if you install from the CD/dvd you can create a shortcut in steam to it. This will let you launch through steam, steam will update your status with what you're playing and enable the steam overlay UI while playing it as well. nearly all the benefits. you'll still need to have the CD in while playing and steam will not auto-patch it.