Wi-Lan, a Canadian firm that holds lots of patents and makes no products, has sued 22 firms over Wi-Fi and DSL power consumption patents: They venue shopped and sued in the Texas court known for finding in favor of patentholders. Firms sued include Apple, Atheros, Belkin, Broadcom, Buffalo, Intel, Marvell, and NetGear. The rights of patentholders that have no competitive products were circumscribed by the Supreme Court to limit their power in getting injunctions. But patent-holding firms that exist to license still have plenty of rights. Some of these firms are called patent trolls, but I can't see Wi-Lan getting that sobriquet because their portfolio is targeted and descends from actual product work. Others may feel differently.
There's a lot of propaganda around about 'patent trolls', most of it in my opinion spun in the interests of large players who have enjoyed trampling on IP rights for too long. If you're big enough, you don't have to pay for the little guy's patents, but instead others have to license your portfolio (e.g.IBM generates over $1B in licensing revenues each year etc.).
As a private investor in Wi-Lan, people seem to forget Wi-Lan's pivotal role in opening up unlicensed spectrum to wireless communications with the FCC, leading to the development of major market segments for wireless products.