BlackBerry Plugin 2.5 for VS 2008 is now depreciated! You no longer can use it and RIM doesn’t support it.
Moreover they updated the tool set and emulators at one place!
Now you can take advantage of HTML 5, to develop Web & Native apps for BlackBerry devices!
You can download the tools from the below link –
Documentation – https://bdsc.webapps.blackberry.com/html5/documentation
API Reference – https://bdsc.webapps.blackberry.com/html5/api
You can take advantage of Ripple emulator to test you apps – both Web & Native.