GovWin offers a "short examination of the historical spending data on the ESI [Enterprise Software Initiative] program examines which vendors are winning the most business, what COTS software DoD customers are buying, and what the implications of expanding the ESI program might be."
Here's the takeaway graphic and quote (below the chart) for geospatial:
The Top 10 DoD ESI Vendors
" The presence of ESRI in the top 10 vendors indicates the value the DoD sees in expanding the use of geospatial capabilities."
And, maybe, I'll toss in, further explains the aqusition of GeoIQ. I thought Google might be in there too, but I think Carahsoft sells their enterprise geospatial products.