I haven't said anything about the allegations that Syria has provided Hizbullah in Lebanon with Scud missiles because, so far, the allegations from Israeli leaders, echoed by some in the US, haven't been backed up with satellite photography or other evidence.
Before adding some comments of my own, a few other takes on the matter. Andrew Tabler of WINEP, posting at Foreign Policy, has a moderately hawkish take; Josh Landis of Syria Comment, also writing at Foreign Policy's Middle East channel, offers a more cautious, skeptical take. The Arabist understands why Hizbullah might want them, and Qifa Nabki satirizes the whole story. Syria has vehemently denied the story, and Hizbullah says it's none of Israel's business.
The whole thing has cast a shadow over US efforts to open dialogue with Syria, and could delay Robert Ford's Senate confirmation as the first US Ambassador in Damascus since the Hariri assassination. (The Foreign Relations Committee cleared the nomination earlier this week; it goes to the full Senate.)
I have no direct knowledge of what evidence may exist; US sources are quoted as not being sure the missiles have entered Lebanon. There were earlier reports that Syria had transferred Igla-S shoulder-launched SAMs to Hizbullah, but that's clearly a defense weapon against low-flying aircraft, not a long-range surface-to-surface missile.
Even the SCUD-D, supposedly involved here, is not very up-to-date technology, but their transfer to a non-state actor would be provocative at a time when Israel seems to be itching for an excuse to go another round with Hizbullah. I'm therefore skeptical and would like to see some evidence. When you're talking about a game-changing move, as Israel is seeking to portray this, you need pretty convincing evidence. I know SCUD launchers are easy to hide. But if Israel has photos (satellite, RPV, or otherwise) they should release them. Think Adlai Stevenson putting up the U-2 photos at the UN during the Cuban Missile Crisis while the Russians floundered about their denials.
With that, I'm off for the weekend.