Yesterday, Microsoft released the CTP of SQL Express with Advanced Services. You can use this distro to get SSRS functionality in Express.
Here's the section of the readme that applies to "us" (bold is mine):
4.2 Creating Reports by Using Reporting Services and Business Intelligence Development Studio
Setup installs Reporting Services. After you install Reporting Services, you can view reports against relational data on the local computer.
Because Reporting Services in SQL Server Express is supported on a local server only, you must install Reporting Services and the SQL Server Express Database Engine on the same computer.
To create reports by using Reporting Services, you must also install Business Intelligence Development Studio.
Business Intelligence Development Studio is the Microsoft Visual Studio 2005 environment with enhancements that are specific to SQL Server 2005 business intelligence solutions.
Business Intelligence Development Studio is available as part of Microsoft SQL Server 2005 Express Edition Toolkit (SQL Server Express Toolkit). SQL Server Express Toolkit installs the design tools that are used to create reports. SQL Server Express Toolkit is available for download at this
Microsoft Web site.
...and here's where you can download it: