Hi Parker,
As far as I recall, the Agentry Plug-in sits under "SAP Mobile SDK 2.3".
Inside that download ZIP there should be a file called Agentry-Dev-Tools-2.3.zip
That's where you will find the Agentry Eclipse plug-in (for 32 and 64-bit environments) as well as Agentry Test Environment utility and the Agentry standalone Dev server.
The plug-in should work on both SMP and standalone Dev Agentry server, however there is an issue when running the standalone Dev Agentry server as a "Windows service" (refer to earlier reply from Bill Froelich)
Also, from what I understand, SAP are now advising customers to move from standalone Agentry to SMP. Standalone Agentry for development purposes is OK. But for proper deployment, hosting and monitoring of production Agentry apps, the recommendation going forward is to use SMP.
Hope this helps.
Regards,
Roman.