Are there solar panels that integrate photovoltaic and thermal systems?

Yes, historically they have been called hybrid solar collectors.  More specifically they are called PV/T collectors which is short for photovoltaic/thermal collectors. The commercial products that are currently available are: http://echofirst.com/ http://sundrumsolar.com/index.php/products http://www.dawnsolar.com/faq.html#3 These solutions have not seen big success yet because they aren't as cost effective as separate panels doing the separate functions.   Dawn Solar is arguably the best looking thermal panel available because it looks just like metal roofing.  Because of this, it is really the only "building integrated photovoltaic/thermal" product available.  Unfortunately, its thermal efficiency is very poor.  (See the SRCC rating at http://www.solar-rating.org/ratings/index.html ) As roof space becomes more important as a potential source of energy, hybrid panels may also become more important.

I can help to make the list a bit longer, here are the 21 companies I know about:   http://www.enfsolar.com/directory/panel/6341/absolicon, http://www.enfsolar.com/directory/panel/6433/berken-energy, http://www.enfsolar.com/directory/panel/22826/c-bosch, http://www.enfsolar.com/directory/panel/6250/conserval-engineering, http://www.enfsolar.com/directory/panel/23148/eleos-distribution-enr, http://www.enfsolar.com/directory/panel/307/entech-solar, http://www.enfsolar.com/directory/panel/9567/everlight-corporation, http://www.enfsolar.com/directory/panel/11246/fototherm, http://www.enfsolar.com/directory/panel/4845/holtkamp-ses, http://www.enfsolar.com/directory/panel/1443/millennium-electric-tou, http://www.enfsolar.com/directory/panel/23528/photonics-power, http://www.enfsolar.com/directory/panel/22762/poly-solar-solutions, http://www.enfsolar.com/directory/panel/2130/pvt-austria, http://www.enfsolar.com/directory/panel/12538/quadra-solar, http://www.enfsolar.com/directory/panel/6248/solarhybrid, http://www.enfsolar.com/directory/panel/6251/solarzentrum-allgau, http://www.enfsolar.com/directory/panel/16820/solecho, http://www.enfsolar.com/directory/panel/20597/waris, http://www.enfsolar.com/directory/panel/7372/wiosun, http://www.enfsolar.com/directory/panel/6345/zenithsolar and http://www.enfsolar.com/directory/panel/14474/zhuhai-tianke.   All these companies should be commercially active.  I'm going to check out the 3 companies that Kevin mentioned, nice to see some others we didn't know about.

To add to Kevin's list, there is also a Swill company called Panotron (http://www.panotron.com/de/index.php?page=2724), which combines both solar hot water and solar photovoltaic panels. (The page is in German, however.) There was some joint research undertaken by MIT and Boston College to combine the two technologies (http://www.solarchoice.net.au/blog/photovoltaic-and-solarthermal-hybrid-technology-mit-and-boston-college/) as well.

At Luminalt, we've worked with EchoFirst. One of the drawbacks is that it requires a very particular installation site, including attic space. Working mostly in San Francisco, with its older housing stock, many homes don't meet the physical requirements. In recent years, we've lessened our presence in the residential solar thermal market because of the price of copper - a good solar hot water system (like good plumbing in general) will use copper pipes and fittings. For gyms or commercial kitchens with volume, it begins to make more financial sense (for example, we installed solar hot water at Project Open Hand in downtown San Francisco). With the cheap prices of natural gas, and the tier-rate structure of electricity, installing solar electric tends to make more financial sense. As Bill Fridl mentions, solar electric requires virtually no maintenance, while solar hot water has moving parts that can fail (as with any plumbing).