Plenty of companies, whether they know it or not. Large companies like IBM are very cautious when it comes to code ownership and contamination. In some companies, employees have an easier time going through their divorce than getting an approval by an open source committee to use GPL software.
I'd expect IBM, of all "big companies," to be one of the least concerned about an acquisition using GPL software. They do so much work with GPL software, I'm sure they have very well defined internal policies on making sure they're in compliance. IBM is number 7 by measure of changesets (http://lwn.net/Articles/460597/) in the 3.1 Linux kernel.
Heck, my company (approx 150k employees) isn't what I'd consider a good contributor to open source software but even we have internal policies defining how we need to comply with GPL and other open source licenses. There's lawyers internally that specifically work with open source compliance.
As long as you have your act together and can show that you're compliant with all licenses (open or closed), I can't see why it would be a major barrier to a legit buyout offer.
A can attest that at my first employer (Britain's semiconductor flagship - well respected inside and outside open source communities), getting approval for open source libraries was a true pain. It took many months, with lawyers having to go over every file, and approval was never certain.
