I never considered this design, and will be installing at least 3 of these blocks at home and at the garden for Spring 2011!!!
The above photo is by Brian Murphy of Mt. Diablo Audubon, and was given to Bay Nature, a nature magazine about the San Fransisco Bay. Their article that features this photo, "Back Yard Boarding House - How a Power Drill Can Attract Pollinators" is right up my alley - and should be up your alley too! Of course, there are dozens or hundreds of potential designs for bee houses, including those with liners. Check out these plans from USDA, Washington State University, National Wildlife Federation, the dependable folks at eHow, and a very useful post at the Phig Blog. For those of us with less free time but just as much enthusiasm, bee blocks, liners, and even dormant bees can be purchased all over the internet, from Mason Bee Homes to Andrew's Reclaimed to Territorial Seed and Pollinator Paradise.
Let me know how your bees do - I promise you'll hear about mine.