I have a Mac mini server 2011, currently have a SSD with 2 partitions, 1 for bootcamp win 7 and the other one for OS lion. Will there be any improvements if I add a second SSD and use a dedicated SSD for each OS. thanks for the advice
There would be no inherent advantage. A separate SSD for each would obviously give them more room to work with, but a secondary SSD does that too.
Theoretically - it may even be beneficial for the data to be split between the drives, as your machine will be able to simultaneously send read/write requests to both the OS SSD and the 'storage' SSD; e.g. when loading software with certain standard libraries which might be hosted within the system.
It does get a little harder to organize though, as you may need to remember where everything is located. Symlinks or mounting within the primary partition can compensate for that though.