Good question, I go to the Developers Tab > Packages > Installed Packages > Umbraco Courier and it gives me the Package version.

That's right, but if a manual upgrade has taken place, this number might not be the currently installed version.

I need this as well. Looking in the Developer->Packages->Installed Packages area only gets me "Umbraco Courier for Umbraco 6". I need to be able to get more specifics (e.g. 2.7.8.35 or 2.7.8.43). Does anyone have a workaround to figure out what version is installed?

An issue has been created in the courier issue tracker to deal with this. http://issues.umbraco.org/issue/COU-35

I just made this. I hope it helps someone else. You can use it to figure out what version of courier you have installed. The data here assumes you have courier 2.7.8.x and have courier for umbraco 6. I just downloaded all the current versions from the umbraco nightlies at http://nightly.umbraco.org/UmbracoCourier/2.7.8/nightly%20builds/ and found the file versions on the Umbraco.Courier.Core.dll file for each version of Courier.

Courier Version     Umbraco.Courier.Core.dll file version   
  2.7.8.5               1.0.4904.22311
  2.7.8.7               1.0.4904.39638
  2.7.8.8               1.0.4920.23940
  2.7.8.9               1.0.4920.25412
  2.7.8.11              1.0.4926.25732
  2.7.8.12              1.0.4927.17831
  2.7.8.13              1.0.4931.23852
  2.7.8.14              1.0.4933.38233
  2.7.8.15              1.0.4937.27040
  2.7.8.16              1.0.4940.22079
  2.7.8.17              1.0.5004.14835
  2.7.8.18              1.0.5077.27239
  2.7.8.19              1.0.5077.27768
  2.7.8.30              1.0.5098.25519
  2.7.8.31              1.0.5102.21177
  2.7.8.33              1.0.5102.22395
  2.7.8.34              1.0.5115.30005
  2.7.8.35              1.0.5121.26836
  2.7.8.36              1.0.5136.26300
  2.7.8.37              1.0.5210.14555
  2.7.8.38              1.0.5210.17784
  2.7.8.39              1.0.5225.21626
  2.7.8.40              1.0.5232.23892
  2.7.8.41              1.0.5284.17386
  2.7.8.42              1.0.5323.40480
  2.7.8.43              1.0.5324.14383

Also, it is very likely that I have some typos in here.

is working on a reply...