Re: No surprise
Not sure about the building logo (although I think it was kept), but RSA kept its own logo and .com address after being acquired by EMC. Pretty sure VMware did too, with just a small line under each logo, identifying it as an EMC company. That was a conscious decision on EMC's part since each of those companies already had a strong identity and customer base, and it was worth keeping their existing branding.
But who knows what Dell will do? Sometimes it's about the ego, rather than what the branding brings to the acquiring company.