Health Insurance Restrictions and Limitations Clarification Act of 2008 - Amends the Employee Retirement Income Security Act (ERISA), the Public Health Service Act, and the Internal Revenue Code to exclude a group health plan from prohibitions against limitations or restrictions on the amount, level, extent, or nature of the benefits of coverage for similarly situated individuals enrolled in the plan so long as: (1) such limitations and restrictions are explicit and clear; (2) such limitations and restrictions have been disclosed to the plan sponsor in writing in advance of the point of sale; (3) the plan sponsor provides a description of such limitations and restrictions to participants and beneficiaries in a form that is easily understandable before enrollment; and (4) the plan sponsor and the issuer of the coverage provide such description to the participants and beneficiaries upon their enrollment under the plan at the earliest opportunity that other materials are provided.