Sun had a nice patent portfolio too. Some of Google's current initiatives, like being part of the OpenPower Alliance, might have benefited from the hardware acquisition as well with RISC being all the rage again. Having Solaris in their back pocket would have been handy and ZFS might have been re-licensed to be more GPL friendly as well.

I'm not sure how much of that Google could directly benefit from but they could have definitely gain a metric fkton of community good will by opening many of the technologies Sun owned that have floundered since the Oracle acquisition.