In both the 0.9.1 stable and 0.9.2 snapshot, only Degree, In-Degree, and Out-Degree appear as options for node sizes (despite not running any statistics, so the values are null). After running eigenvector centrality there is no option to assign it as a node size - I copied the column, converted it to float, and it still does not show up on the list. This may be similar to #1479

Stats for my system:
Java: 1.8.0_74; Java HotSpot(TM) 64-Bit Server VM 25.74-b02
Runtime: Java(TM) SE Runtime Environment 1.8.0_74-b02
System: Mac OS X version 10.11.4 running on x86_64; UTF-8; en_US (gephi)