Lately I've been trying to come to some conclusions on Jesus' burial.
It seems highly probable to me that Jesus was buried somewhere, however, the question of whether the burial was simply in a hole in the ground or a tomb is difficult to sort out.
It has been suggested by some (i.e. John Dominic Crossan) that Jesus was simply left on the cross and not given a burial. But look at Deuteronomy 21:22-23:
"If someone guilty of a capital offense is put to death and their body is exposed on a pole, you must not leave the body hanging on the pole overnight. Be sure to bury it that same day, because anyone who is hung on a pole is under God’s curse. You must not desecrate the land the LORD your God is giving you as an inheritance." (Note that some translations say "tree" instead of "pole").
This theme is repeated throughout Jewish literature: that even criminals are supposed to buried, and therefore it is likely that Jesus would have been buried, at least if the Jewish authorities had any say-so in the matter. And they probably did, for there is evidence that during peacetime Roman authorities would comply with the local Jewish customs. See chapter 2 of Doubting Jesus' Resurrection
Also note that Shimon Gibson concurs with this on page 132 of The Final Days of Jesus: The Archaeological Evidence
Last night I was reading something on google.books but I can no longer find it. It was discussing John Dominic Crossan's suggestion that most (perhaps all) criminals in first-century Palestine were simply tossed in burial pits. Against this claim was an archaeological find in which a skeleton was found in a tomb with a nail lodged in its foot. Crossan claimed that the fact that the we have only one skeleton of a crucified victim in a tomb proves that it was the exception and not the rule. Against this claim it was shown that crucifixion did not always involve nails and that when it did the nails were often removed because they were reguarded as having magical powers (in this particular find the nail wasn't removed because it was stuck between the bones). I'd say, on this issue, Crossan is completely wrong. The fact that we have a skeleton with such an usual feature (having the nail stuck in bones) would be something very rare, and we would only be likely to make such a find if many other crucified victims were buried in tombs (the other victims would not, of course, be recognizable as victims of crucifixion because of reasons mentioned previously).
So, based on what I've found so far, burial in a tomb is at least plausible, although some of the details in Mark's story are not. Burial in the ground is also plausible, I think, and I know of no good evidence that would render ground-burial-of-Jesus implausible.
In future posts concerning this issue I won't bring up Jesus' burial in a tomb as a point of contention, since, as I've said, I consider it to be a highly plausible hypothesis (though I don't consider it proven or greatly superior to the ground burial hypothesis).