The granddaddies of HIP Beethoven cycles are the Hogwood and Norrington sets. Of the two, I prefer the Hogwood. Other great HIP cycles include the Gardiner and Brüggen. Gardiner's set has a sweeter tone than the Brüggen, whose sound can be a bit harsh. Of all the HIP cycles, the Brüggen is probably the most radical sounding. At this point, I think the Brüggen cycle is oop, but sets can still be found at reasonable price from some vendors. It never had wide release in the USA and it's almost impossible to find here. I hate to admit it, but I haven't cracked the cellophane on the Tafelmusik Beethoven 5th and 6th. There's been too much to do lately. FWIW, the two most popular of these cycles are the Gardiner and Hogwood, with sound quality on the Gardiner a bit better than the older cycle. The first Norrington cycle is not a particular favorite of mine. Although Gramophone cited it as one of the most important (or best) Beethoven cycles ever made, I really don't think that it wore very well. His second cycle with more conventional forces is preferable.
Zig-Zag Territoires has announced that that Immerseel's Beethoven cycle will be released in 2008:
This [Ravel Bolero]
is the last project of Anima Eterna before the complete symphonies of Beethoven which will be released in 2008 ! As you can see on their concerts’ agenda, many Beethoven concerts are scheduled to prepare this big event. Strangely, this was in the information for the Ravel Bolero recording on the Zig-Zag website. There is no other mention of it at all, anywhere. It's certainly something to look forward to.
The only HIP Savall Beethoven symphony recording I have is the Eroica which I like very much, but many people really hate that recording. I don't know if he's actually done more than that. The sound that Savall gets is closer to baroque than classical; but it's filled with a rough energy that appeals to me. Good luck finding that one, as I suspect it's long oop.

Another thing that we should consider are the hybrid cycles (Dausgaard, Zinman, Harnoncourt, Fey) which use scaled down conventional orchestras, limit the vibrato of the string sections, use either older brass instruments or hand stopping techniques, etc. Although they don't use period instruments, they are informed by Historic research and practice. I n er know whether they should be discussed in HIP threads or not.