I have gotten a handful of inquiries about an older version of Jupiter that is compatible with Eclipse 3.1.x which is what BEA Workshop 9.2 is based off of. I just wanted to let you know that I don't have Jupiter for Eclipse 3.1.x and because of numerous repository changes I do not have the source code dating back that far. I didn't start working on Jupiter until after 3.2.1 came out so I do not have anything older than that on the Jupiter homepage. I apologize for the inconvenience.
Also, I have seen someone mention that it does not work with Aptana Studio. I installed Aptana Studio myself and installed Jupiter just to see. I dug around and it says that the current version of Aptana Studio is based on Eclipse 3.2.2. I know the current version of Jupiter (3.4.1.1) works with Eclipse 3.2.2. I don't see any reason why it shouldn't show up in Aptana Studio. It says Jupiter is installed and that it is working. I dug through the log file and while I saw an overwhelming amount of exceptions, none of them said anything about Jupiter. So to those who are using Aptana Studio, I'm sorry I don't have any idea why Jupiter doesn't work.
And finally, I have been asked about Jupiter and Adobe FlexBuilder. I also downloaded Adobe FlexBuilder and installed Jupiter. It is based on Eclipse Europa (3.3) so in theory it should work. But it doesn't. It lets you install Jupiter but I don't see it listed in the plugins after it restarts. The log file has no indication of problems so I'm not sure what is going on there. So I also don't have any idea why it does not work with Adobe FlexBuilder.
This is probably not what some of you wanted to hear and I apologize.
Just a note that I normally only test Jupiter against Eclipse for RCP/Plug-in Developers from http://www.eclipse.org/downloads.
