I don't hear of many startups using Oracle, IBM mainframes or proprietary Unix either. I think there is a general aversion among startups to using expensive technology, and I think the reasons are fairly obvious.
If you're interested in the startup world, learn another software stack or three. Startups generally need people who learn new things quickly and use the best tool for the job. Flexibility is key; don't be a one-trick pony.
I actually heard of a "green energy" startup that listed Oracle and Crystal Reports as a requirement. It was one of those grotesque things started by lawyers and energy veterans.
I usually latch on to people with extensive domain expertise outside of computing, just to see where things might lead, but that particular one felt very FAILy and the people too unreachable and bureaucratic (i.e. "fax the requirements to my office and I will tell the girl to embed them inside the spreadsheet" -- horrible.)
If you're interested in the startup world, learn another software stack or three. Startups generally need people who learn new things quickly and use the best tool for the job. Flexibility is key; don't be a one-trick pony.