The company I used to work for made Java app servers, and we certified our product on various platforms. We certified on Solaris 2.6 for one version, but needed some updated libraries from 2.7 for the next. Unfortunately, so many of our customers refused to use 2.7 that they didn't buy that product. Other things happened to the company before they got around to certifying it on 2.8.
If you're considering 2.8 for anything, though, remember that just like any Solaris version, without the appropriate patch level... it'll have problems