Here's the report, published Tuesday. An excerpt from the Summary:

The two main criteria which the courts would likely look to in order to determine whether legislation is a bill of attainder are (1) whether "specific" individuals or entities are affected by the statute, and (2) whether the legislation inflicts a "punishment" on those individuals. Under the instant bills, the fact that ACORN and its affiliates are named in the legislation for differential treatment would appear to meet a per se criteria for specificity.

The U.S. Supreme Court has also identified three types of legislation which would fulfill the "punishment" prong of the test: (1) where the burden is such as has "traditionally" been found to be punitive; (2) where the type and severity of burdens imposed are the "functional equivalent" of punishment because they cannot reasonably be said to further "non-punitive legislative purposes;" and (3) where the legislative record evinces a "congressional intent to punish." The withholding of federal contracts or grants does not appear to be a "traditional" punishment, nor does the legislative record so far appear to clearly evince an intent to punish. The question of whether the instant legislation serves as the functional equivalent of a punishment, however, is more difficult to ascertain.

While the regulatory purpose of ensuring that federal funds are properly spent is a legitimate one, it is not clear that imposing a permanent government-wide ban on contracting with or providing grants to ACORN fits that purpose, at least when the ban is applied to ACORN and its affiliates jointly and severally. In theory, under the House bill, the behavior of a single employee from a single affiliate could affect not only ACORN but all of its 361 affiliates. Thus, there may be issues raised by characterizing this legislation as purely regulatory in nature. While the Supreme Court has noted that the courts will generally defer to Congress as to the regulatory purpose of a statute absent clear proof of punitive intent, there appear to be potential issues raised with attempting to find a rational non-punitive regulatory purpose for this legislation. Thus, it appears that a court may have a sufficient basis to overcome the presumption of constitutionality, and find that it violates the prohibition against bills of attainder.

My much more tentative thoughts on the subject are here.