I have generated an SSH key on Ubuntu 10.04 with
ssh-keygen -t rsa -C "example@example.com"
and the key's random art image comes out mostly empty (modified slightly):
+--[ RSA 2048]----+
| |
| |
| |
| |
| D |
| s.J |
| Bv.++= |
| =ooo.=o+ |
| c .+*.+o. |
+-----------------+
Does that indicate an issue with the random number generator?