Two year warranties are provided on most other Optoma projectors as well, along with all of the Epson Home Cinema series projectors, Mitsubishi home theater projectors, and those from Planar, plus several of the higher end brands.
When it comes to projectors with three year warranties, Optoma's higher end 1080p projectors, the HD81 and HD81-LV come with three. Epson provides three years on their Pro Cinema series projectors, and BenQ has three on their higher end W20000.
Some of the projectors mentioned have overnight replacement programs. Epson provides the replacement service for their full warranty length - two and three years respectively for the Home and Pro Cinema lines. BenQ offers a first year replacement on the W20000.
Bottom line: The Optoma HD806 warranty is below average. Though I'm not particularly a fan of 3rd party extended warranties, they tend to be very inexpensive, and I have to recommend them for projectors with a single year warranty standard, as you definitely won't enjoy having to pay for an out of warranty repair in the second year you own the HD806. Projector repairs tend to be very expensive.