Send To > Play has "Play (shuffled)" and "Add (shuffled)". Does that help?
Not in my view of how shuffled play mode should work...
For example:
1) Turn Shuffle On
2) Select 5 albums and right-click Play
Result A: 5 albums are placed in Playing Now and shuffled nicely
3) Play songs for a while (somewhere beyond track 1)
4) Decide I'd like to hear some more from a specific Artist/Genre/...
5) Select another album and right-click Add to Playing Now
Result B: 5 albums shuffled nicely, 1 album with it's tracks shuffled added to the end of the Playing Now list. Hmm not what I wanted
6) Delete new album from playing now
7) Select the album again and right-click Send To->Play->Add (shuffled)
Result C: Dang, same thing as Result B
Delete new album from playing now again
9) Select the new album and right-click Send To->Play->Add (shuffle all)
Result D: Doh! Now the songs I've already heard are shuffled back in!
10) Grab my playing now back from Playlists->Recent Playing Now's
12) Select the new album and right-click Add to Playing Now
13) Go to Playing Now and select all the unplayed tracks and right-click Shuffle
Result E: Doh! I guess Shuffle isn't selection based! Same as Result E
14) Grab my playing now back from Playlists->Recent Playing Now's
15) Delete all tracks in Playing Now before the currently playing one
16) Select the new album and right-click Send To->Play->Add (shuffle all)
Result F: Finally what I wanted: Shuffle the new tracks into the unheard tracks in Playing Now.
I got what I wanted, but not in an obvious or user friendly way. Also, I had to trash my listening history to get it... To top it off, there's no way to duplicate this in Theater View.
Why can't Add to Playing Now when Shuffle Mode is on just shuffle my tracks in with the unplayed tracks?
How often do you want to add an album in non-track # order to the end of the current Playing Now list?
-John