The market keeps on moving: SAP acquires Sybase etc. But one name attracted my attention: GemStone being acquired by VMWare/SpringSource (next to RabbitMQ, Hyperic, …).
Time flies: I remember Gemstone as a vendor of OODBMS and application server. On the OODBMS side there were also Versant, ObjectStore (eXelon –> Progress). The list of applicaton servers – just before EJB’s took off – is much longer: Netscape Applicaton Server, Forté, Jaguar CTS (Sybase), Tengah (became WebLogic), IBM Component Broker, ATG Dynamo, Novell Silverstream, Novera, … Had forgotten about most of them. Another such “hidden” company that I recently encountered is Pramati.

