I've done it the past two years...2007 was great, 2008 was miserable. Wind made all the difference--this year it was headwind the whole way, for the first time in over 10 years. My friend quit at noon the first day, I bagged it at lunch on the 2nd day.

It does sell out really fast--registration opens in October, and last year it sold out in 11 days. Corporate teams sometimes have reserved spots if you miss the general registration, but unless you work for a company with a team or know someone that does, I wouldn't count on that option.

The ride dates for 2009 are 4/18-4/19, but I'm not sure when registration opens. In the past, it's been early-to-mid October, so I would keep an eye on the website starting late this month. (http://ms150.org/ms150)

As for hills...there are some rollers on the first day, but they're in the 2nd half of the route...from Houston to the lunch stop in Bellville is fairly flat. Most the hills are on the 2nd day, and you have a choice of going straight up Hwy 71 (higher traffic, no shade, but more gradual hills) to the lunch stop or going through the state park (lots of short steep rollers). I've done both, and prefer the park. The uphills are hard, but you can really pick up some speed on the descents. There's also an option to go toward the park but then short-cut across and go straight into Bastrop. I've heard that route is kind of a happy medium between the "lunch express" (Hwy 71) and the "challenge route" (park), though I've never done it. The elevation maps for the route are here.

Unless there's a change in route from 2007, there's a good set of big rollers coming into Austin also. They look nasty, but you can get enough momentum going down to make it most of the way up the next one without an enormous effort.

Finally, about finding a place to stay. If you're not planning on riding with a team or camping at the fairgrounds in La Grange, plan on booking your hotel/lodgings EARLY. Most more affordable hotels are booked solid right after the previous MS150 (people I've talked to have said that those that stay there just book every weekend for the month of April in the next year, then cancel the other weekends once they know the event dates). Sometimes you can get lucky and find something after the cancellation deadline in March, but to be safe I would start looking for a room now. This page will tell you which hotels have shuttle service to/from the fairgrounds, but be forewarned--you may get a driver that has no idea where your hotel is. Those volunteers come from all over, and may not know the area any better than you do. I stayed at the Hyatt Lost Pines last year, and the shuttle bus ride there was 2 hours long, with half the passengers having to tell the bus driver where to turn to get to their hotels. Not fun. (That hotel was nice, btw, but I won't be staying there again. Too spendy.) RV parks are another option...I have a friend who went in with a group renting an RV the last two years, and he highly recommends it. Ends up being about the same cost as local hotels, and a lot less hassle. There are several parks around the fairgrounds...not sure how fast they fill up, though.