Fortunately for both of us, the Open Font Licence FAQ explicitly addresses this question:
Can I make and use WOFF (Web Open Font Format) versions of OFL fonts?
Yes, but you need to be careful. A change in font format normally is considered modification, and Reserved Font Names (RFNs) cannot be used. Because of the design of the WOFF format, however, it is possible to create a WOFF version that is not considered modification, and so would not require a name change. You are allowed to create, use and distribute a WOFF version of an OFL font without changing the font name, but only if:
- the original font data remains unchanged except for WOFF compression, and
- WOFF-specific metadata is either omitted altogether or present and includes, unaltered, the contents of all equivalent metadata in the original font.
If the original font data or metadata is changed, or the WOFF-specific metadata is incomplete, the font must be considered a Modified Version, the OFL restrictions would apply and the name of the font must be changed: any RFNs cannot be used and copyright notices and licensing information must be included and cannot be deleted or modified. You must come up with a unique name - we recommend one corresponding to your domain or your particular web application. Be aware that only the original author(s) can use RFNs. This is to prevent collisions between a derivative tuned to your audience and the original upstream version and so to reduce confusion.
Please note that most WOFF conversion tools and online services do not meet the two requirements listed above, and so their output must be considered a Modified Version. So be very careful and check to be sure that the tool or service you're using is compressing unchanged data and completely and accurately reflecting the original font metadata.
So: if you want to do it with minimal effort, change the font name and fulfil the other obligations shown above. If you want to keep the font name, do due-diligence on your tool of choice, and pick a better tool if it doesn't pass muster.